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Hey guys,

I'm going to check out an e30 tomorrow and the guy claims that the car will drive for 20 or minutes, then it cuts off. He did a full tune up and it continues to do it. Is this a sign of the fuel pump going out? Any good DIY's around that anyone has seen?

I'll be trading it with one of my beaters if everything looks good.

Thanks in advanced!
 

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D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
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31,082 Posts
I'm guessing coil overheating. Not likely a FP would run that long and quit more than once, certainly not consistantly.
 

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livin large
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7,557 Posts
the coil would need to be replaced if its gettin hot. that issue is gunna be more electrical then anything else. ive seen fuel pumps do crazy things, but not consistently
 

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East Bound And Down
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2,852 Posts
it could be the fuel pump... i saw my buddies vert display the same symptoms but it was because the tank was really gummed up and the pump would overheat itself after spirited driving. but i would lean more towards the coil as well.

btw i have 3 e30 coils sitting in the back of my jeep right now. PM me if you want one (for the cost of shipping)
 

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D'oh, You Kids!
1984 633CSi, 1985 635CSi, 1985 325e, 1987 325is, 1993 325is, 1995 318is, 1995 M3, 2003 F150
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31,082 Posts
When you say "coil overheating", does that mean the motor is overheating? Or does the coil need to be replaced?
Not the motor, just the ignition coil. The coil is nothing but a lot of wire wound into a small package. It's really a 'step-up' transformer, but it's only designed for pulses (a whole lot of them really fast) rather than a continuous current like the transformer in front of your house. As the coil ages the insulation between the windings breaks down. That results in the coil heating up and eventually it will fail due to internal damage, either shorting between the windings or opening up one side of the circuit. A normal coil will get pretty warm in use, but not HOT. Next time it dies after running ~20 minutes CAREFULLY touch the coil and see if it isn't blazing hot (a non-contact infrared thermometer would be a lot safer).

You can also test the coil for resistance with a digital meter (done when it's cold).
 

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Git
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324 Posts
Spend 20 minutes with it.
have your ear close to the fuel pump, just before the engine stalls.
Try to discover if the engine dies, then 0.5-1 sec later the pump dies.
If that happens, the pump is ok. 2x check by jumping the relay.
If the car does not start withing 1 hour, I would suspect a coil problem or melted catalytic converter matrix shifting rear wards and blocking off the exhaust.
No air out= No air in= No engine.

m
 

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My 87 325e would die consistently after about 20 minutes. Then would not re-start for about an hour. Ended up being crank position sensor. It runs very well after replacing them ( 2 on my car, Only 1 CPS on your car). It does mimic bad fuel pump and bad fuel pump relay--and like others have said possibly a bad coil. I replaced my fuel pump, fuel pump relay and main relay thinking it was those, before I narrowed it down and my indy also helped diagnose the bad CPS. Good luck.
 
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