Mechanics

FUEL DELIVERY PROBLEM

1985 BMW 318

Engine Performance problem
1985 BMW 318 4 cyl Two Wheel Drive Manual

Vehicle starts, runs about 8 seconds then cuts off and on then recovers and runs fine until parked for a few hours. I replaced the fuel filter, no change. The vehicle acts as though air gets in the fuel line, does some sputtering until the line is solid fuel again. It started about 3 weeks ago and seems to be getting worse.
All help is appreciated.
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Bigbuckhagan
June 18, 2010.



Does this occur when the fuel tank is completely full? There is a internal fuel transfer pump in the tank, but it only helps move the fuel to the main pump when the level is low. Check this site: http://www.realoem.com/bmw/showparts.do?model=1374&mospid=47315&btnr=16_0046&hg=16&fg=05

Dr. Hagerty
Jun 19, 2010.
Full or not it is consistent. Took off this morning went 4 miles and parked vehicle for 15 minutes. Restarted vehicle and took off, when I reached 3rd gear motor was intermittently sputtering, hit 4th gear a few sputters then everything is fine. Fuel tank is full. While vehicle was idling I placed my fingers around the discharge side of the fuel line about 4 " from the fuel pump and could feel intermittent turbulence. Without access to a fuel pressure gauge I have to suspect a failing pump. Car runs fine after it gets over the initial sputtering phase. Thanks for the response.

Tiny
Bigbuckhagan
Jun 19, 2010.
Diagnosis of fuel pressure issues should include a waveform analysis, maybe the pump is not getting power.

Dr. Hagerty
Jun 19, 2010.