Car Randomly Wont Start... 2 Years Later

[Vefu]

I bought my E30 over 2 years ago now, and since I've had it has always had a starting problem. The car starts about 75% of the time, but the other 25% it will just crank and never start.

I've taken it to 3 different mechanics, the first 2 told me they couldn't do anything for the car. Finally a few weeks ago I had it looked at by a different mechanic and he replaced the fuel pressure regulator and said the problem is fixed.

The issue still isn't gone, I've had the car smoke checked and there aren't any vacuum leaks. The fuel pressure regulator was replaced, but other than that I haven't tried to fix anything else.

The only strange thing is when it wont start, the car can still be push started with no issues.

Does anyone have any ideas for me? I'd really like to get this issue taken care of.

[noid]

Crank positioning sensor.

[Frankus12]

no, has to do with the starting circuit if you can push it and it starts fine. theres a relay underneath the knee bolster thats a part of it, and of course the main relays in the fuse box. ide replace all of them. to be sure, next time its not starting, remove the knee bolster and give all those relays in there a good knocking about. and in the fuse box as well.

[noid]

no, has to do with the starting circuit if you can push it and it starts fine. theres a relay underneath the knee bolster thats a part of it, and of course the main relays in the fuse box. ide replace all of them. to be sure, next time its not starting, remove the knee bolster and give all those relays in there a good knocking about. and in the fuse box as well.

A failing CPS can produce a weak signal during starting yet with a running engine can produce enough signal to run fine (same logic when bump starting). Often producing intermittent starting.

I'm sorry but your logic makes little sense when his car cranks and runs 75% of the time.

[Frankus12]

My car does the same thing, perhaps at an 80/20 rate, it's the sticking start relay underneath the dash found on automatic models. If I kick the bolster it usually starts. Your explanation is logical regarding the CPS as well. If the P.O. Has an auto, it's a possibility I should've said.

[noid]

I do not own an automatic, however I would imagine the start relay would prevent the starter from getting a ground to turn over if it couldn't confirm it was in P or N.

I would also really love to see someone push start an automatic.

[henryki]

Had the same problem in mine. Thought it was a faulty fuel pump, turns out it was the CPS, when you go to order one there's a plastic and a metal option, the metal one IMO is the way to go.