M20 floods on warm restart

[The Dark Side of Will]

Car: 1987 325iX manual

I just got Bad Idea back on the road after fixing a whole of of things that were "fixed" by the previous maintainer.

It floods on a warm restart. I can fire the car up cold and it starts readily. I drive for 1-5 minutes, shut it off and leave it for a couple of minutes. When I come back and try to restart, it floods. I can crank and crank and it won't start; I smell a LOT of fuel out the tailpipe.
If I remove the fuel pump relay, it will crank for a few seconds, then run for a couple of seconds on residual pressure in the fuel rail, then die.

Sometimes I can replace the fuel relay and start it right back up. However this morning I had to stand by the fender, reach through the open door to crank and pop the relay back in when it started because it was still flooding when I tried to restart otherwise.

Is there a common sensor failure (e.g. intake air temp) which causes this behavior?

Do the Bosch EFI systems have a "flood clear mode"? On GM systems from the late '80's and early '90's, flooring the gas pedal while cranking turns off the injectors and allows the engine to clear a flood, but that doesn't appear to work on the Bosch system.

Did the '87's still have cold start injectors?

It runs great most of the time, but on idling after a cold start, it will run the RPM up to 2000-2500 for a couple of minutes, then drop down to 600-800 for a couple of minutes, then back up to 2000-2500, etc.

[mpowerful]

Coolant twmp sensor for the injectors. Its either white or blue topped with two wires. Not brown with one wire. Change it out. They are like 10 bucks at autozone.

[The Dark Side of Will]

You mean these?



Both of those are two wire sensors. You say the blue one goes to the DME and the brown one goes to the dash gauge?

I also have this problem: http://www.e30tech.com/forum/showpos...&postcount=689

In addition to the injector wires, all four of those temp sensor wires were involved. I simply replaced the previous maintainer's trash splices with good ones. Since both of the returns/grounds are brown with no stripe, the guy who hacked up those splices may have swapped them, which means I left them swapped.

I guess I need to get out the multi-meter and make sure those wires go where they're supposed to go before I drop dollars on parts.

[jlevie]

I can't see the engine temperature changing enough in 1-5 minutes of operation to affect starting. But I can see leaking injectors as causing a problem.

[mpowerful]

^^ True.....

[Nutzy]

FPR's are known to leak internally and run fuel back into the manifold. My old 84 323i was doing this, hot starts were a bitch!

[The Dark Side of Will]

Interesting... and easy enough to check.

[jlevie]

FPR's are known to leak internally and run fuel back into the manifold. My old 84 323i was doing this, hot starts were a bitch!

Good point! A bad diaphragm in the FPR would leak fuel into the intake.

[AlphaE]

I have a similar problem.. Except it would start if i just floored it a bit..i got a new blue CTS and have swapped out the FPR and it still did it. The last thing i did was remove, take apart and clean the Main relay. I also took apart, cleaned up and "retracked" the AFM. Hasnt done it since. But it was very intermittent and its only been a few weeks. But could be worth a try.