Fuel pump, Relay, DME???? Car wont start

[10isPro]

93 318IS
slushbox tranny


yesterday driving to work I hit a bump and the CEL light flashed, RPMs dropped like it wanted to stall, but kept driving fine after that and when I came home.

Today,

Went about 2 blocks and hit a bump, it did it again. another 2 blocks did it again
CEL light flashes, almost stalls

It does this 2more times in 10minutes

Then about 25miles from my house and 3miles from work, I hit 3 bumps in a row and it did it each time and finally stalled.
managed to get off side of the road and it restarted

Got another mile or 2 and it did it again, but this time it would not restart

I plugged my PEAK tool in and it continues to read "E" which means it cant communicate with the DME

Called Tow company to pick me up to get car home and sat and waited.

I figured I would try and unhook the battery and reset the DEM while I sat and wait. I was missing the right socket to loosen my Bat terminals enough to get them off but I did loosen the negative a little.
and then My car restarted.....

and I was able to drive it about 200yards...

Towed home and been trying to diagnose for a couple hours


Fuel Pump relay socket shows voltage at pin 86 but not 30 with no relay in it.
But it shows voltage randomly.
I can check it once and it shows voltage, check it again and nothing
NO voltage on either w/ Key in ACC

Same with Main relay, no voltage on any positive terminal.

I even tried putting in a DEM from an extra Engine I have
Same problems.


Anyone have any ideas what else to check?

[10isPro]

voltage sometimes will read 12v on 30 only on FP relay. I had 12v on 86 and 30 on the Main relay

Key in ACC--voltage drops to 3.2v on both FP and Main relay.

No voltage on pin 86 on FP relay.

[10isPro]

Anyone?
its my only car and I cant keep using my wife's car and leaving her stranded at home with 2 little ones

[10isPro]

hmm noone knows

[whonneb]

MIne worked fine and now it will not start. I was thinking more along the lines of the crankshaft sensor for my problem. Do you even know if you are getting gas to the engine. Have you check the fuel pressure? Where did you locate the fuel pump relay?

[whonneb]

Probally not the same problem

[m2pc]

10ispro (nice alias, I get it! :D)

It really sounds like a loose connection, especially if the problems all coincide with "bumps" in the road. I would check all the connections in the engine bay (especially those circular plugs near the fuse box) to make sure they're all tight.

Could also be a loose ground wire/strap or even the +12v leads from the battery -> jump start block -> starter. It could also be a short circuit (wire rubbing on the frame or some other metal)... maybe check the trunk wiring harness? Our cars are famous for having problems in that area -- do a search on the forums or Google (search feature is on the fritz here lately) for "e36 trunk wiring short" and it should come up with some info.

Any one of these loose connections could affect the ECU.

[10isPro]

10ispro (nice alias, I get it! :D)

It really sounds like a loose connection, especially if the problems all coincide with "bumps" in the road. I would check all the connections in the engine bay (especially those circular plugs near the fuse box) to make sure they're all tight.

Could also be a loose ground wire/strap or even the +12v leads from the battery -> jump start block -> starter. It could also be a short circuit (wire rubbing on the frame or some other metal)... maybe check the trunk wiring harness? Our cars are famous for having problems in that area -- do a search on the forums or Google (search feature is on the fritz here lately) for "e36 trunk wiring short" and it should come up with some info.

Any one of these loose connections could affect the ECU.


i def think it is electrical. I havent had time to see if the fuel pump is even kicking on anymore, But something is causing the fuel pump to kick off.

I too think could be a ground issue, but where is the question.
Bentley manual says that the ground for the MAIN RELAY, comes from the DME if I read right..DME provides trigger for FP relay...

Sunday I'll have time to check more out,

If anyone else has any ideas, much appreciate