FINALLY - I think I have figured it out....
A long post but I thought some of you might wish to read...
Background:
1987 Westfalia w/ 1994 OBD-1 EJ22/25 Frankenmotor w/?starting?issue;
- Normally the engine?starts?right up (just a few seconds of cranking)
- A few times now it has taken a long time?or wouldn't fire up at all
- Still cranked perfectly?normally (high torque starter running fast)
- Also, occasionally, when I turned the key to the 'Run' position and didn't go straight to 'Start', the CEL flashed On and Off repeatedly plus I heard the fuel pump relay clicking in the back
Latest update and final (I hope) diagnosis/fix:
- Main fuse to the ECU was burned.
- There is a 20A fuse in a dustproof?fuse holder feeding the ECU; in my van this is next to the ECU under the seat (some folks seem to put the two relays in the black terminal box in the engine compartment?)
- From outside all looked good; the top of the fuse also looked good (I checked this early on in my search)
- HOWEVER, inside, the fuse body and contacts were melted/blackened (the fuse hadn't blown it was just making a bad connection; I suspect it had come loose at some point)
- enough extra resistance to drop the supply to the ECU and that in turn caused the fuel pump relay to 'chatter' and drop out. No fuel pressure at START = No Engine Start.
- Replacing the fuse holder and fuse with a 'MAXI' version (more metal contact area) gives me NORMAL Starting/Running once more - At LAST!
How did I find this: I tried using a DVM and LED bulbs to probe power and signals around the ECU, relays, ignition switch etc. but I only really identified it using my oscilloscope; it was so transient and hard to find.
One?blind alley I took;
(1). fuel pressure collapsing rapidly after the fuel pump turned off (I powered the fuel pump direct and tee-d in a fuel pressure gauge)?
- it's supposed to remain?above 30 psi after 15 minutes: indicated to me a fuel leak/delivery issue. No hose leaks apparent
- I changed the fuel pump & filter - NO impact
- SO I thought this must be the fuel pressure regulator or leaky injectors; took them out, replaced them all. NO impact?
- Back to the fuel pump: 2nd replacement was good; now I got solid fuel pressure?(although incorrect - see my following post)
==> Two bad fuel pumps!! All part of my?luck!
(2). Other things I changed (unnecessarily as it seems...)
- new fuel pump and ignition relays- new ignition switch
- swapped out the?ECU
- added a new major ground strap chassis to engine (previously?heavy duty cables battery to engine). Main battery voltage?~12.2V (and the engine cranked just fine)
FINALLY - a < $1 part seems to have failed (and I spent ~$600 on new parts and many hours to figure it out...)
Thanks for suggestions as I worked through this; hopefully my van is good again
