BMW Starting Problems

[Rick Iverson]

Gents;

Our oldest has a BMW track car. Starting from cold, it fires up immediately, but after thirty minutes of hard track time followed by a cool down period until the next session, quite frequently he will drain the battery cranking.

He has swapped out chips, ECUs, spark plugs, fuel filter etc., with no joy. Thoughts?

[t walgamuth]

Sounds like vaporlock.

[Rick Iverson]

Sounds like vaporlock.

Yep, that’s what I recommended. There is also a noticeable absence of a faint “clicking” noise from a relay that primes the fuel pump sometimes in starting after a session. But I surmise he has swapped it out also. I’ll check with him.

I recall my HS auto shop teacher in Mr. Robinson recommending a cloths pin on the metal fuel line just prior to the carburetor. But that was 1967.

[ExKartracer]

Fuel pressure regulator or check valve in fuel pump leaking. Fuel pressure should hold for some time after shut down.