Mechanics

BMW 733I ENGINE PROBLEM

1984 BMW 733i • 145,000 miles

While driving down the road the engine suddenly stops running. Each time I try to start the engine runs for 1 or 2 seconds and the stops again. After several tries the engine keeps running. I have noticed that after the car has been running for a while and I stop the RPM fluctuates up and down. The engine suddenly stopping is comming more and more frequently.
Thank you,
Ray.
Avatar
1984E23
December 18, 2012.



Check fuel pressure.

Merlin2021
Dec 18, 2012.
The fuel pressure is fine. We also recently changed the fuel filter. I think it is something electrical. This BMW has alot of electrical components, I probably need a response from someone that is familiar with older BMW's and familiar with the electrical components and which one would cause these symptoms.

Tiny
1984E23
Dec 19, 2012.
Does it only happen on deacceleration and idle? Or all the time?

Merlin2021
Dec 19, 2012.
It happens mostly at in town speeds and idle. Generally runs fine at highway speeds.

Tiny
1984E23
Dec 20, 2012.
Have you checked throttle body, and IAC? Clean all ports of carbon? And PVC system is a biggie, dry rot of vacuum hoses and PCV gasket.

Merlin2021
Dec 20, 2012.
I agree with Merlin. The items on his list need to be checked and eliminated from the equation. I also have some input as to the idle air control, it is usually quite robust on that car and I have not seen them fail, however, diagnosis of that system would start with checking for power at the IAC valve/connector and resistance at the IAC valve. With the key on and the engine off, the valve should be felt to vibrate, if not, you have a problem with the IAC, let us know what you come up against mate.

Dr. Hagerty
Dec 29, 2012.