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Oregon to legalize pumping your own gas. https://www.thedrive.com/news/oregon-finally-legalizes-pumping-your-own-gas-after-72-years
I'm pretty sure my evap problems started when an overzealous gasoline attendant overfilled my gas tank years ago.?
My decade-long boycott of Oregon gas stations can finally end! ?:-)
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When I'm in Oregon, i just ignore the law and fill my own tank, experience experience experience...... Have replaced various parts for years before i figured it out. Glad to no longer be a scofflaw
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Has anyone had any success or failure this summer with the gas fume issue?
My prior fix was to install a GM vapor canister, detailed here: ?
That made a big improvement, and I thought the problem was 100% solved, until I did one trip last summer in extreme conditions (105F+ temperatures) where I had some fume venting when stopping at 7500' altitude.
Here's what I have planned for the upcoming hot + high trips:
1. I gently bent the metal tab / spring in the fuel filler neck. ?The gas cap, when fully screwed in, presses on this metal part which opens the breather valve. ?Others have mentioned this being a fix, and it's logical that this spring could gradually bend over the years and cause partial or complete failure of the evap system. ?(See attached picture)
2. replaced my N-80 purge valve. ?The prior one tested fine, but I had a brand new Bosch brand model, so I figured it couldn't hurt.
3. I'm going to bring an IR thermometer and FLIR camera and hope to get some data on the gas tank temperature.
4. I'd love to get some data on the N-80 operation, but not sure how to capture that. ?Does VCDS have a parameter to measure it?
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We're having failure with it right now. It started last summer, at altitude and hot, but when we returned home to sea level it resolved, and since the van isn't driven much it wasn't an issue and I neglected it.
Now we're having pressure build up in the tank and it'll miss under load, like going up hills, and sometimes at idle. Not sure if it's related to the tank issue but it seems to be. No codes. I just did the metal tab/spring in the filler neck so I'll see if that helps. I'll report back.
David 2000 EVC
On Sunday, July 9, 2023 at 10:37:27 AM PDT, Michael Diehr <md03@...> wrote:
Has anyone had any success or failure this summer with the gas fume issue?
My prior fix was to install a GM vapor canister, detailed here: ?
That made a big improvement, and I thought the problem was 100% solved, until I did one trip last summer in extreme conditions (105F+ temperatures) where I had some fume venting when stopping at 7500' altitude.
Here's what I have planned for the upcoming hot + high trips:
1. I gently bent the metal tab / spring in the fuel filler neck. ?The gas cap, when fully screwed in, presses on this metal part which opens the breather valve. ?Others have mentioned this being a fix, and it's logical that this spring could gradually bend over the years and cause partial or complete failure of the evap system. ?(See attached picture)
2. replaced my N-80 purge valve. ?The prior one tested fine, but I had a brand new Bosch brand model, so I figured it couldn't hurt.
3. I'm going to bring an IR thermometer and FLIR camera and hope to get some data on the gas tank temperature.
4. I'd love to get some data on the N-80 operation, but not sure how to capture that. ?Does VCDS have a parameter to measure it?
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I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
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On Jul 13, 2023, at 4:57 PM, Michael Diehr <md03@...> wrote:
?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block?
A
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On Jul 13, 2023, at 14:43, Jerome B Dwight <jeromebdwight@...> wrote:
That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
On Jul 13, 2023, at 4:57 PM, Michael Diehr <md03@...> wrote:
?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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Fortunately, all of the fumes are outside the vehicle, so it's not quite that dangerous, but I share your concern and would like to get this fixed.
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On Jul 13, 2023, at 2:43 PM, Jerome B Dwight <jeromebdwight@...> wrote:
That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
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This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank. Is there some reason it does a loop rather than just a one-way trip? And if is doing a round trip, could there be some failure mode in this system?
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On Jul 13, 2023, at 3:23 PM, Alex L <amlevy@...> wrote:
Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block?
A
On Jul 13, 2023, at 14:43, Jerome B Dwight <jeromebdwight@...> wrote:
That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
On Jul 13, 2023, at 4:57 PM, Michael Diehr <md03@...> wrote:
?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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Round trip is normal for this era of vehicle. It’s only in the last decade or so since they quit using a return line
I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank
But I suspect the problem is heat is getting into the fuel lines. From where and how is the question
In the hot rod world we had a problem very similar to this. People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick. The solution was to use a PCM (pulse controlled) pump. Not a solution for us
Back to the tank pressure, isn’t that supposed to vent out through the carbon canister?
Stephen
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On Jul 13, 2023, at 6:11 PM, Michael Diehr <md03@...> wrote:
?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank. Is there some reason it does a loop rather than just a one-way trip? And if is doing a round trip, could there be some failure mode in this system?
On Jul 13, 2023, at 3:23 PM, Alex L <amlevy@...> wrote:
Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block?
A
On Jul 13, 2023, at 14:43, Jerome B Dwight <jeromebdwight@...> wrote: That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
On Jul 13, 2023, at 4:57 PM, Michael Diehr <md03@...> wrote:
?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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Good ideas - I've also been trying to think of things that could cause the tank to be pressurized...
- LDP : I believe the LDP does pressurize the tank and then does a leak-down test. I believe it also closes the vent line and N80 valve, to test a fully closed system. With the vent and N80closed, vapors can not pass through the canister to be adsorbed or be burnt through the purge system. Could the LDP get stuck in "test" mode? That might explain everything, though my van has no emissions codes, so seems unlikely.
- pressure back flowing from the N80 purge valve? If somehow the intake manifold was not at vacuum, but under pressure, then the N80 opening could allow pressure back into the fuel tank. I'm pretty sure this is not possible, because (A) if the intake manifold has positive pressure and your engine is not turbocharged, things are going very wrong, and (B) I think the N80 flows only one direction, and I think there's a check valve between the carbon canister and the tank.
- Pressure / altitude : I used to think this was mainly a heat issue, but my recent experience says otherwise: everything was fine with a very hot but gradual trip up to about 4000', but only when I headed up to 6000' then 7500' did things go wrong, even though ambient temperatures were going down by then. Also, when I measured the gas/gas tank it was only 120F, which doesn't seem that hot to me.
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On Jul 13, 2023, at 5:53 PM, Stephen Jackson <register@...> wrote:
Round trip is normal for this era of vehicle. It’s only in the last decade or so since they quit using a return line
I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank
But I suspect the problem is heat is getting into the fuel lines. From where and how is the question
In the hot rod world we had a problem very similar to this. People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick. The solution was to use a PCM (pulse controlled) pump. Not a solution for us
Back to the tank pressure, isn’t that supposed to vent out through the carbon canister?
Stephen
On Jul 13, 2023, at 6:11 PM, Michael Diehr <md03@...> wrote:
?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank. Is there some reason it does a loop rather than just a one-way trip? And if is doing a round trip, could there be some failure mode in this system?
On Jul 13, 2023, at 3:23 PM, Alex L <amlevy@...> wrote:
Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block?
A
On Jul 13, 2023, at 14:43, Jerome B Dwight <jeromebdwight@...> wrote: That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
On Jul 13, 2023, at 4:57 PM, Michael Diehr <md03@...> wrote:
?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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Bingo - this was a recall from my car racing/hot rod days with similar era vehicles. The fuel pump runs at one speed, so it necessarily must be calibrated to full throttle/full load. If it’s less than that, excess fuel must return to the tank, otherwise the system is under too much pressure and kablooey. I believe standard pressure in the gas tank is ~2 psi to prime the pump at start. Beyond that unhelpful.
To Stephen’s point - two issues.
1) vapor in fuel line does not happen on its own. Heat is the culprit somewhere. Small engine bay w/ poor airflow, iron block and exhaust header = lots of heat soak. We already know about issues with heat on the engine and transmission fluids. Not surprising it would affect fuel system too. Try placing insulated heat shield between the exhaust header/flexpipe/downpipe and the fuel lines. There are also fuel line heat wraps available. Look at Jegs or Summit Racing- auto racing supply outlets.
2) *some* vapor is expected, hence the carbon canister. Could be partially or fully plugged, not flowing enough? Michael, I know you spent significant effort with the modified canister. Is there another vapor release valve somewhere?
Also - since it presents at altitude/high heat, I’m inferring that air density might be an issue. Less air = more fuel vapor. Overwhelms the venting system?
More armchair opinions…
Alex
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On Jul 13, 2023, at 17:53, Stephen Jackson <register@...> wrote:
Round trip is normal for this era of vehicle. It’s only in the last decade or so since they quit using a return line
I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank
But I suspect the problem is heat is getting into the fuel lines. From where and how is the question
In the hot rod world we had a problem very similar to this. People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick. The solution was to use a PCM (pulse controlled) pump. Not a solution for us
Back to the tank pressure, isn’t that supposed to vent out through the carbon canister?
Stephen
On Jul 13, 2023, at 6:11 PM, Michael Diehr <md03@...> wrote:
?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank. Is there some reason it does a loop rather than just a one-way trip? And if is doing a round trip, could there be some failure mode in this system?
On Jul 13, 2023, at 3:23 PM, Alex L <amlevy@...> wrote:
Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block?
A
On Jul 13, 2023, at 14:43, Jerome B Dwight <jeromebdwight@...> wrote: That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes.
On Jul 13, 2023, at 4:57 PM, Michael Diehr <md03@...> wrote:
?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth. (7000' elevation). It's a roughly 3000' elevation gain in about 30 miles. Temperatures were hot but not exceptional (95F or so).
As I got above 6000' I noticed gas fumes while driving. Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).
I opened the gas cap and vented the tank until it stopped outgassing. It was a tremendous amount of gas. Once all pressure was gone, I continued on to my destination which is over 7500'.
I was no longer smelling fumes at that level, but after I stopped, I did a test. The engine was still running.
I opened the gas cap. Again, there was tons of gas escaping, as well as some drops of liquid gasoline.
- with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank: about 120F. Warm, but really not hot enough to account for this great volume of vapor.
Here's where it gets interesting:
- I stopped the engine, and the vapor quickly stopped.
- I started the engine again, and within seconds, the vapor is flowing out of the gas tank again.
- I stopped the engine, and the vapor stops.
This feels like an important clue: why did stopping the engine stop the vapor?
Mike
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On Thu, Jul 13, 2023 at 08:25 PM, Michael Diehr wrote:
I've also been trying to think of things that could cause the tank to be pressurized.
Here's the VW EVAP study guide - everything you want to know. -- Duane 05HD Rialta 225K Miles
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A cautionary tale:
?
The fuel lines on my 1997 EVC had deteriorated and developed a SERIOUS leak. The lines are hard plastic with rubber connections at several points). I was smelling gas fumes and I originally chased the EVAP system to no avail. A deep dive revealed a serious leak on the return line where the rubber line bent to connect to the fuel pump.?
?
It’s a total hassle, but check those fuel lines. These vans are old and rubber doesn’t last forever.
?
Related: The fuel lines are NLA. Repairing or replacing them is probably possible via a hydraulic hose shop. I replaced the hard lines with high pressure fuel injection lines from NAPA.?
?
Kris
1997 EVC
245,000 miles
Original engine and transmission
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I bought a 1995 with 180K. Replaced the fuel lines as a precaution and a whole?host of other stuff. I just don't like hoping for the best when it comes to crossing the country.?
A cautionary tale:
?
The fuel lines on my 1997 EVC had deteriorated and developed a SERIOUS leak. The lines are hard plastic with rubber connections at several points). I was smelling gas fumes and I originally chased the EVAP system to no avail. A deep dive revealed a serious leak on the return line where the rubber line bent to connect to the fuel pump.?
?
It’s a total hassle, but check those fuel lines. These vans are old and rubber doesn’t last forever.
?
Related: The fuel lines are NLA. Repairing or replacing them is probably possible via a hydraulic hose shop. I replaced the hard lines with high pressure fuel injection lines from NAPA.?
?
Kris
1997 EVC
245,000 miles
Original engine and transmission
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That's funny, we just did the same drive last Saturday with similar problems that I responded to in the other thread.
When I stopped for gas in Bishop the tank released pressure for about 10 minutes. Had a really hard time pulling up Sherwin summit on 395 and again up to Convict Lake. Released pressure again for a long time at Convict. Next morning was cooler but I didn't tighten the cap all the way and opened the cap at every stop along the way to release pressure. Bought a new cap in Gardnerville but didn't put it on till Truckee (and it was so-so up the hill to Tahoe) and did the spring bend maneuver.? So far so good, no pressure build up and no strange missing like before but don't feel it has really been tested because it hasn't been that hot and we haven't driven over 30-40 minutes at one time. Sunday we go to Reno and back up 80, so that will be a good test. I can let you know how it goes.
David 2000 EVC
On Thursday, July 13, 2023 at 06:25:33 PM PDT, Michael Diehr <md03@...> wrote:
Good ideas - I've also been trying to think of things that could cause the tank to be pressurized... - LDP : I believe the LDP does pressurize the tank and then does a leak-down test. I believe it also closes the vent line and N80 valve, to test a fully closed system.? With the vent and N80closed, vapors can not pass through the canister to be adsorbed or be burnt through the purge system.? Could the LDP get stuck in "test" mode?? That might explain everything, though my van has no emissions codes, so seems unlikely. - pressure back flowing from the N80 purge valve?? If somehow the intake manifold was not at vacuum, but under pressure, then the N80 opening could allow pressure back into the fuel tank.? I'm pretty sure this is not possible, because (A) if the intake manifold has positive pressure and your engine is not turbocharged, things are going very wrong, and (B) I think the N80 flows only one direction, and I think there's a check valve between the carbon canister and the tank. - Pressure / altitude : I used to think this was mainly a heat issue, but my recent experience says otherwise: everything was fine with a very hot but gradual trip up to about 4000', but only when I headed up to 6000' then 7500' did things go wrong, even though ambient temperatures were going down by then.? Also, when I measured the gas/gas tank it was only 120F, which doesn't seem that hot to me. > On Jul 13, 2023, at 5:53 PM, Stephen Jackson < register@...> wrote: > > Round trip is normal for this era of vehicle.? It’s only in the last decade or so since they quit using a return line > > I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank > > But I suspect the problem is heat is getting into the fuel lines. From where and how is the question > > In the hot rod world we had a problem very similar to this.? People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick.? The solution was to use a PCM (pulse controlled) pump. Not a solution for us > > Back to the tank pressure, isn’t that supposed to vent out through the carbon canister? > > Stephen >> On Jul 13, 2023, at 6:11 PM, Michael Diehr < md03@...> wrote: >> >> ?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank.? Is there some reason it does a loop rather than just a one-way trip?? And if is doing a round trip, could there be some failure mode in this system?? >> >>> On Jul 13, 2023, at 3:23 PM, Alex L < amlevy@...> wrote: >>> >>> Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block? >>> A >>> >>> >>>>> On Jul 13, 2023, at 14:43, Jerome B Dwight < jeromebdwight@...> wrote: >>>> >>>> That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes. >>>>> On Jul 13, 2023, at 4:57 PM, Michael Diehr < md03@...> wrote: >>>>> >>>>> ?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth.? (7000' elevation).? It's a roughly 3000' elevation gain in about 30 miles.? Temperatures were hot but not exceptional (95F or so). >>>>> >>>>> As I got above 6000' I noticed gas fumes while driving.? Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).? >>>>> >>>>> I opened the gas cap and vented the tank until it stopped outgassing.? It was a tremendous amount of gas.? Once all pressure was gone, I continued on to my destination which is over 7500'.? >>>>> >>>>> I was no longer smelling fumes at that level, but after I stopped, I did a test.? The engine was still running. >>>>> >>>>> I opened the gas cap.? Again, there was tons of gas escaping, as well as some drops of liquid gasoline. >>>>> >>>>> - with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank:? about 120F.? Warm, but really not hot enough to account for this great volume of vapor. >>>>> >>>>> Here's where it gets interesting: >>>>> >>>>> - I stopped the engine, and the vapor quickly stopped. >>>>> - I started the engine again, and within seconds, the vapor is flowing out of the gas tank again. >>>>> - I stopped the engine, and the vapor stops. >>>>> >>>>> This feels like an important clue: why did stopping the engine stop the vapor? >>>>> >>>>> Mike >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> >> > > > > > >
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Ten minutes?
The filler hose is a decent size diameter. ?I mean it takes 3-5 minutes to fill the tank?
Could you also check the tank temp when this happens? ??
I live in Colorado and do similar climbs and have not had this problem, so I am interested.?
I run primarily alcohol free gas, not sure if that matters
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On Jul 14, 2023, at 1:05 PM, monicact@... wrote:
?
That's funny, we just did the same drive last Saturday with similar problems that I responded to in the other thread.
When I stopped for gas in Bishop the tank released pressure for about 10 minutes. Had a really hard time pulling up Sherwin summit on 395 and again up to Convict Lake. Released pressure again for a long time at Convict. Next morning was cooler but I didn't tighten the cap all the way and opened the cap at every stop along the way to release pressure. Bought a new cap in Gardnerville but didn't put it on till Truckee (and it was so-so up the hill to Tahoe) and did the spring bend maneuver.? So far so good, no pressure build up and no strange missing like before but don't feel it has really been tested because it hasn't been that hot and we haven't driven over 30-40 minutes at one time. Sunday we go to Reno and back up 80, so that will be a good test. I can let you know how it goes.
David 2000 EVC
On Thursday, July 13, 2023 at 06:25:33 PM PDT, Michael Diehr <md03@...> wrote:
Good ideas - I've also been trying to think of things that could cause the tank to be pressurized... - LDP : I believe the LDP does pressurize the tank and then does a leak-down test. I believe it also closes the vent line and N80 valve, to test a fully closed system.? With the vent and N80closed, vapors can not pass through the canister to be adsorbed or be burnt through the purge system.? Could the LDP get stuck in "test" mode?? That might explain everything, though my van has no emissions codes, so seems unlikely. - pressure back flowing from the N80 purge valve?? If somehow the intake manifold was not at vacuum, but under pressure, then the N80 opening could allow pressure back into the fuel tank.? I'm pretty sure this is not possible, because (A) if the intake manifold has positive pressure and your engine is not turbocharged, things are going very wrong, and (B) I think the N80 flows only one direction, and I think there's a check valve between the carbon canister and the tank. - Pressure / altitude : I used to think this was mainly a heat issue, but my recent experience says otherwise: everything was fine with a very hot but gradual trip up to about 4000', but only when I headed up to 6000' then 7500' did things go wrong, even though ambient temperatures were going down by then.? Also, when I measured the gas/gas tank it was only 120F, which doesn't seem that hot to me. > On Jul 13, 2023, at 5:53 PM, Stephen Jackson < register@...> wrote: > > Round trip is normal for this era of vehicle.? It’s only in the last decade or so since they quit using a return line > > I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank > > But I suspect the problem is heat is getting into the fuel lines. From where and how is the question > > In the hot rod world we had a problem very similar to this.? People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick.? The solution was to use a PCM (pulse controlled) pump. Not a solution for us > > Back to the tank pressure, isn’t that supposed to vent out through the carbon canister? > > Stephen >> On Jul 13, 2023, at 6:11 PM, Michael Diehr < md03@...> wrote: >> >> ?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank.? Is there some reason it does a loop rather than just a one-way trip?? And if is doing a round trip, could there be some failure mode in this system?? >> >>> On Jul 13, 2023, at 3:23 PM, Alex L < amlevy@...> wrote: >>> >>> Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block? >>> A >>> >>> >>>>> On Jul 13, 2023, at 14:43, Jerome B Dwight < jeromebdwight@...> wrote: >>>> >>>> That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes. >>>>> On Jul 13, 2023, at 4:57 PM, Michael Diehr < md03@...> wrote: >>>>> >>>>> ?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth.? (7000' elevation).? It's a roughly 3000' elevation gain in about 30 miles.? Temperatures were hot but not exceptional (95F or so). >>>>> >>>>> As I got above 6000' I noticed gas fumes while driving.? Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).? >>>>> >>>>> I opened the gas cap and vented the tank until it stopped outgassing.? It was a tremendous amount of gas.? Once all pressure was gone, I continued on to my destination which is over 7500'.? >>>>> >>>>> I was no longer smelling fumes at that level, but after I stopped, I did a test.? The engine was still running. >>>>> >>>>> I opened the gas cap.? Again, there was tons of gas escaping, as well as some drops of liquid gasoline. >>>>> >>>>> - with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank:? about 120F.? Warm, but really not hot enough to account for this great volume of vapor. >>>>> >>>>> Here's where it gets interesting: >>>>> >>>>> - I stopped the engine, and the vapor quickly stopped. >>>>> - I started the engine again, and within seconds, the vapor is flowing out of the gas tank again. >>>>> - I stopped the engine, and the vapor stops. >>>>> >>>>> This feels like an important clue: why did stopping the engine stop the vapor? >>>>> >>>>> Mike >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> >> > > > > > >
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Good point. One metric we haven't captured yet is the gas type.
- Jonathan
On Friday, July 14, 2023 at 05:52:09 PM PDT, Stephen Jackson <register@...> wrote:
Ten minutes?
The filler hose is a decent size diameter. ?I mean it takes 3-5 minutes to fill the tank?
Could you also check the tank temp when this happens? ??
I live in Colorado and do similar climbs and have not had this problem, so I am interested.?
I run primarily alcohol free gas, not sure if that matters
On Jul 14, 2023, at 1:05 PM, monicact@... wrote:
?
That's funny, we just did the same drive last Saturday with similar problems that I responded to in the other thread.
When I stopped for gas in Bishop the tank released pressure for about 10 minutes. Had a really hard time pulling up Sherwin summit on 395 and again up to Convict Lake. Released pressure again for a long time at Convict. Next morning was cooler but I didn't tighten the cap all the way and opened the cap at every stop along the way to release pressure. Bought a new cap in Gardnerville but didn't put it on till Truckee (and it was so-so up the hill to Tahoe) and did the spring bend maneuver.? So far so good, no pressure build up and no strange missing like before but don't feel it has really been tested because it hasn't been that hot and we haven't driven over 30-40 minutes at one time. Sunday we go to Reno and back up 80, so that will be a good test. I can let you know how it goes.
David 2000 EVC
On Thursday, July 13, 2023 at 06:25:33 PM PDT, Michael Diehr <md03@...> wrote:
Good ideas - I've also been trying to think of things that could cause the tank to be pressurized... - LDP : I believe the LDP does pressurize the tank and then does a leak-down test. I believe it also closes the vent line and N80 valve, to test a fully closed system.? With the vent and N80closed, vapors can not pass through the canister to be adsorbed or be burnt through the purge system.? Could the LDP get stuck in "test" mode?? That might explain everything, though my van has no emissions codes, so seems unlikely. - pressure back flowing from the N80 purge valve?? If somehow the intake manifold was not at vacuum, but under pressure, then the N80 opening could allow pressure back into the fuel tank.? I'm pretty sure this is not possible, because (A) if the intake manifold has positive pressure and your engine is not turbocharged, things are going very wrong, and (B) I think the N80 flows only one direction, and I think there's a check valve between the carbon canister and the tank. - Pressure / altitude : I used to think this was mainly a heat issue, but my recent experience says otherwise: everything was fine with a very hot but gradual trip up to about 4000', but only when I headed up to 6000' then 7500' did things go wrong, even though ambient temperatures were going down by then.? Also, when I measured the gas/gas tank it was only 120F, which doesn't seem that hot to me. > On Jul 13, 2023, at 5:53 PM, Stephen Jackson < register@...> wrote: > > Round trip is normal for this era of vehicle.? It’s only in the last decade or so since they quit using a return line > > I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank > > But I suspect the problem is heat is getting into the fuel lines. From where and how is the question > > In the hot rod world we had a problem very similar to this.? People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick.? The solution was to use a PCM (pulse controlled) pump. Not a solution for us > > Back to the tank pressure, isn’t that supposed to vent out through the carbon canister? > > Stephen >> On Jul 13, 2023, at 6:11 PM, Michael Diehr < md03@...> wrote: >> >> ?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank.? Is there some reason it does a loop rather than just a one-way trip?? And if is doing a round trip, could there be some failure mode in this system?? >> >>> On Jul 13, 2023, at 3:23 PM, Alex L < amlevy@...> wrote: >>> >>> Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block? >>> A >>> >>> >>>>> On Jul 13, 2023, at 14:43, Jerome B Dwight < jeromebdwight@...> wrote: >>>> >>>> That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes. >>>>> On Jul 13, 2023, at 4:57 PM, Michael Diehr < md03@...> wrote: >>>>> >>>>> ?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth.? (7000' elevation).? It's a roughly 3000' elevation gain in about 30 miles.? Temperatures were hot but not exceptional (95F or so). >>>>> >>>>> As I got above 6000' I noticed gas fumes while driving.? Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).? >>>>> >>>>> I opened the gas cap and vented the tank until it stopped outgassing.? It was a tremendous amount of gas.? Once all pressure was gone, I continued on to my destination which is over 7500'.? >>>>> >>>>> I was no longer smelling fumes at that level, but after I stopped, I did a test.? The engine was still running. >>>>> >>>>> I opened the gas cap.? Again, there was tons of gas escaping, as well as some drops of liquid gasoline. >>>>> >>>>> - with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank:? about 120F.? Warm, but really not hot enough to account for this great volume of vapor. >>>>> >>>>> Here's where it gets interesting: >>>>> >>>>> - I stopped the engine, and the vapor quickly stopped. >>>>> - I started the engine again, and within seconds, the vapor is flowing out of the gas tank again. >>>>> - I stopped the engine, and the vapor stops. >>>>> >>>>> This feels like an important clue: why did stopping the engine stop the vapor? >>>>> >>>>> Mike >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> >> > > > > > >
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Hello, David, (If your issue is resolved, then this post is moot -- please skip)
?
Right now I'm working on an EVAP issue for my Toyota so thought I’d contribute to this conversation.
EVAP issue include fuel-related components e.g. gas cap, gas filler tube, gas tank, charcoal canister, electrically-controlled solenoid valves etc.
?
Apologies for the long post -- hope I'm not breaking rules.
But EVAP issue are beasts (ask me how I know lol).
QUESTIONS
1. Any MIL codes?
2. Did you buy an OEM gas cap?
3. Does gas pump-handle turn off while you’re refueling before tank is full? Does handle turn off while filling the tank?
THOUGHTS
1. Very little fuel vapor should release after the gas cap is removed — that’s a good indicator where the issue(s) may be. By the way, the gas cap is an integral part of the EVAP system.?(I’d be surprised if the new gas cap solved the issue entirely. If it has, I’ve learned something new!)??
Fuel vapor builds in fuel tank then is “pushed” (by heat or sloshing) to breather bottle then sent to breather valve (see note about OEM caps). Breather valve is closed when refueling. (It’s near the top of the breather bottle and traps air in the bottle so there’s room for fuel vapor from the gas you’re putting in the tank.).
2. Some non-OEM caps aren’t deep enough to open the breather valve to allow fuel vapor expansion in fuel tank.
3. Breather valve should close the top of the breather bottle while you refuel. Fuel vapor passes through rollover valve then to the vapor canister. Fuel vapor passes through canister and “cleaned” then is vented outside.
4. The other side of the venting is the purging from the EVAP purge regulator valve usually near the firewall by the intake manifold. When this valve is opened by the ECM it creates a vacuum that draws fuel vapor from the vapor canister and sucks that vapor into the engine. This gives the EVAP canister more storage space for fuel vapor. The ECM (computer brain of the van) controls the opening/closing of this regulator and relies on data it gets from the oxygen sensors and the MAF sensor (info that controls how well fuel/air mixed in various driving conditions e.g. altitude, speed, etc). Remember, air and gasoline (vapor) are entering the engine as part of the EVAP process..
5. LDP is for the test side of the EVAP system – LDP is primarily used to pressurize the EVAP system. This allows the EMC to measure rate of pressure drop that would indicate a leak. It can also function as the EVAP canister vent. if you’re not throwing MIL codes, then issues aren’t meeting the threshold for those errors. Doesn’t mean that system is okay. It just means the system can't or hasn't seen the error.
ASSUMING YOU HAVE NO MIL (OBD CODES)
1. The EVAP canister purge regulator valve could be blocked or defective (electrical and/or intermittent failure won’t necessarily display MIL).
2. Vent lines might be plugged/pinched.
3. Check them for damage or blockage (spider webs and critter remains can affect these vents!). Also check for restrictions at EVAP canister, EVAP canister vent and the EVAP canister vent valve.
WHERE IS THE ISSUE?
“I opened the gas cap.? Again, there was tons of gas escaping, as well as some drops of liquid gasoline.”
?
1. Liquid gas should not exit the gas filler tube.
2. When gas pump-handles click off while fueling (assuming the fill tube is okay) it’s the system’s way of telling you to stop fueling — “topping off” is one of the single biggest contributors to failing/failed EVAP systems and canisters because raw fuel contaminates the charcoal in the vapor canister. But assume you're not topping off.
3. Also note the breather bottle and the EVAP canister don’t have huge storage for vapor. But in extreme vapor pressure situations in fuel tank, the fuel vapor can be vented through the gas cap which appears is what you're having to do. Possible location "legs" for issues based on your symptoms as described (and assuming O2 sensor and MAF reporting accurately to ECM and no MIL):
a. Gas cap to gas tank
b. Breather bottle to vapor canister (scrutinize the breather bottle and breather valve)
c. Vapor canister to engine intake (hose(s) to purge valve)
d. Stinky MAF and/or O2 sensor (if the data they send to ECM is incorrect, the ECM won’t time the open/close of the EVAP purge valve to suck fuel vapor out of vapor canister. This could cause an increase in fuel tank pressure and force vapor (and gas) up the filler tube beyond the capacity of the intermediate systems up the filler neck. Note an intermittent issue with O2 and MAF sensors won't necessarily force a MIL because of drive-cycle requirements enforced by the ECM.
RECOMMENDATION (assuming no MIL)
1. DIY the EVAP system
2. Consider having the EVAP system tested by a tech who understands your system. This individual would understand the relationship between the mechanical and electrical issues that can affect EVAP systems, especially the oxygen sensors (O2) and MAF (mass air flow) sensor. Could be a simple fix...or an ouchie!
WHAT I’D CONSIDER
(If you have no MIL, then I tend to assume the van has passed the ECM EVAP monitor checks using the LDP pressure function. That’s why I’m leaning towards the purge valve and/or the breather bottle/valve.)
1. I’d start with the EVAP canister purge regulator valve N-80 (could be blocked) in the engine bay then move to the vent side from gas cap to EVAP canister.
You shouldn’t be able to blow through any of the N-80 ports when it’s removed (it’s normally closed). You have to apply a quick 12v to the valve to open while the valve is removed physically from the vehicle. You should hear it click. Then you should be able to blow through the valve while the 12v is applied. Not a high-tech test, but it works for a quick check.
I’m leaning towards an intermittent issue with this valve (tough to diagnose without some solid test experience). I assume the oxygen and MAF sensors are good which I think they may be because of the symptoms you describe.
2. Check for failing breather valve and/or failing/clogged breather bottle.
3. Try simple checks of hoses and electrical connections (kinks, clogs, corrosion, creepy-crawlies in hoses)
4.? Pull out scope and multimeter and pressure transducer
P.S. I’ve owned two VW Beetles (one 65 Wolfsburg convertible with real glass rear window!), a VW Rabbit, two '87 Vanagons and one 1993 Eurovan which I dearly miss. Had my shade-tree nose in their innards from time-to-time.??
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Sure felt like 10 minutes, but didn't time it obviously. Not trying to exaggerate but it was a long time, very striking. At first, real strong whooshing. I would take the cap off then put it back on very loose, then all the way off and it would just keep going ,barely perceptible, but felt with fingers over the opening.? Second time an hour later I just loosen the cap and kept checking it while setting up camp.
I have no way to check tank temp, but am open if you have a suggestion.
I thought it might be the gas. This trip stopped in Mojave for gas, from LA, and no pressure. Then Bishop was the biggest it had ever been, and then again in Gardnerville. So all those places could have different petrol mixes. I don't know anything about it but it crossed my mind.
David 2000 EVC
On Friday, July 14, 2023 at 05:52:11 PM PDT, Stephen Jackson <register@...> wrote:
Ten minutes?
The filler hose is a decent size diameter. ?I mean it takes 3-5 minutes to fill the tank?
Could you also check the tank temp when this happens? ??
I live in Colorado and do similar climbs and have not had this problem, so I am interested.?
I run primarily alcohol free gas, not sure if that matters
On Jul 14, 2023, at 1:05 PM, monicact@... wrote:
?
That's funny, we just did the same drive last Saturday with similar problems that I responded to in the other thread.
When I stopped for gas in Bishop the tank released pressure for about 10 minutes. Had a really hard time pulling up Sherwin summit on 395 and again up to Convict Lake. Released pressure again for a long time at Convict. Next morning was cooler but I didn't tighten the cap all the way and opened the cap at every stop along the way to release pressure. Bought a new cap in Gardnerville but didn't put it on till Truckee (and it was so-so up the hill to Tahoe) and did the spring bend maneuver.? So far so good, no pressure build up and no strange missing like before but don't feel it has really been tested because it hasn't been that hot and we haven't driven over 30-40 minutes at one time. Sunday we go to Reno and back up 80, so that will be a good test. I can let you know how it goes.
David 2000 EVC
On Thursday, July 13, 2023 at 06:25:33 PM PDT, Michael Diehr <md03@...> wrote:
Good ideas - I've also been trying to think of things that could cause the tank to be pressurized... - LDP : I believe the LDP does pressurize the tank and then does a leak-down test. I believe it also closes the vent line and N80 valve, to test a fully closed system.? With the vent and N80closed, vapors can not pass through the canister to be adsorbed or be burnt through the purge system.? Could the LDP get stuck in "test" mode?? That might explain everything, though my van has no emissions codes, so seems unlikely. - pressure back flowing from the N80 purge valve?? If somehow the intake manifold was not at vacuum, but under pressure, then the N80 opening could allow pressure back into the fuel tank.? I'm pretty sure this is not possible, because (A) if the intake manifold has positive pressure and your engine is not turbocharged, things are going very wrong, and (B) I think the N80 flows only one direction, and I think there's a check valve between the carbon canister and the tank. - Pressure / altitude : I used to think this was mainly a heat issue, but my recent experience says otherwise: everything was fine with a very hot but gradual trip up to about 4000', but only when I headed up to 6000' then 7500' did things go wrong, even though ambient temperatures were going down by then.? Also, when I measured the gas/gas tank it was only 120F, which doesn't seem that hot to me. > On Jul 13, 2023, at 5:53 PM, Stephen Jackson < register@...> wrote: > > Round trip is normal for this era of vehicle.? It’s only in the last decade or so since they quit using a return line > > I can’t remember if the leak detection pump draws a vacuum or pressurizes the tank > > But I suspect the problem is heat is getting into the fuel lines. From where and how is the question > > In the hot rod world we had a problem very similar to this.? People were using high volume fuel pumps, that combined with small tanks and summer heat, could boil the gas in the tank, as the pumps were circulating it too quick.? The solution was to use a PCM (pulse controlled) pump. Not a solution for us > > Back to the tank pressure, isn’t that supposed to vent out through the carbon canister? > > Stephen >> On Jul 13, 2023, at 6:11 PM, Michael Diehr < md03@...> wrote: >> >> ?This seems possible. I believe that the fuel pump not only pumps fuel to the engine, but it also flows back to the fuel tank.? Is there some reason it does a loop rather than just a one-way trip?? And if is doing a round trip, could there be some failure mode in this system?? >> >>> On Jul 13, 2023, at 3:23 PM, Alex L < amlevy@...> wrote: >>> >>> Armchair mechanic opinion - gas lines are being heated to/from fuel rail via engine bay, causes vaporization which then gets deposited in the tank on the return line. Try heat wrap on the fuel lines? Or heat shield around exhaust/engine block? >>> A >>> >>> >>>>> On Jul 13, 2023, at 14:43, Jerome B Dwight < jeromebdwight@...> wrote: >>>> >>>> That sounds dangerous to me. A friend was incinerated when he carried gas in his car on a hot day. With the right fuel/air mixture the dome light can ignite the fumes. >>>>> On Jul 13, 2023, at 4:57 PM, Michael Diehr < md03@...> wrote: >>>>> >>>>> ?I repeated my usual drive which triggers the problem: up the 395 through Bishop (roughly 4000' elevation) then up the steep climb towards Mammoth.? (7000' elevation).? It's a roughly 3000' elevation gain in about 30 miles.? Temperatures were hot but not exceptional (95F or so). >>>>> >>>>> As I got above 6000' I noticed gas fumes while driving.? Pulled over, turned off the engine. Got out of the van, could not locate the source but it seemed to be near the tank (not in the engine compartment, not the tailpipe).? >>>>> >>>>> I opened the gas cap and vented the tank until it stopped outgassing.? It was a tremendous amount of gas.? Once all pressure was gone, I continued on to my destination which is over 7500'.? >>>>> >>>>> I was no longer smelling fumes at that level, but after I stopped, I did a test.? The engine was still running. >>>>> >>>>> I opened the gas cap.? Again, there was tons of gas escaping, as well as some drops of liquid gasoline. >>>>> >>>>> - with an IR thermometer, I measured the temperatures of the gas tank exterior and gas coming out of the tank:? about 120F.? Warm, but really not hot enough to account for this great volume of vapor. >>>>> >>>>> Here's where it gets interesting: >>>>> >>>>> - I stopped the engine, and the vapor quickly stopped. >>>>> - I started the engine again, and within seconds, the vapor is flowing out of the gas tank again. >>>>> - I stopped the engine, and the vapor stops. >>>>> >>>>> This feels like an important clue: why did stopping the engine stop the vapor? >>>>> >>>>> Mike >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> >> > > > > > >
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Duane
Kris S. Seago