Is there an answer out there? 2 Forums and many $'s later....

[Tiger]

Sounds like you got a hot engine start problem, if so, then that is a simple fix... the checkvalve at the fuel pump is bad thus causing vapor lock at the enigne area. Fuel need to be kept pressurized or otherwise it will turn into gas.

The simple fix is install E39 checkvalve kit. Lots of info on the web ont his matter.

[AussieE34Touring]

Guy's,

This is my M50 525i warm starting hair puller. The car will NOT start until up to 3 attempts have been made once engine is warm. When cold, first time every time.

1) Recent advice is to pull the fuel pump (in situ within tank) and replace. AUD$800. (reluctant)
2) I've had the injectors cleaned $350. No luck there.
3) Aftermarket Immobiliser has been spoken of recently by new mechanic who claims this may be possible cause.
4) O2 sensor has ben checked and is ok.

Is there anyone out there in Bimmer land who has any ideas?

Cheers,
Chris.

[gmannino]

More details please.

Does the car not even try to start? or does it crank?
How long does it crank before starting?
Explain exactly what is happening.

I doubt your aftermarket immobilizer is causing this issue unless it doesnt even try to crank.

[Blitzkrieg Bob]

If the starter turns but the car won't start warm, then I'd look at the following:

Check valve on the fuel pump, may not be holding pressure, pull the fuel line off the injector rail while hot..if you get a face full of gas...it's good.

check the CPS to see if it's good when hot.

Check the Main relay and fuel pump relay when hot.

If the starter does not crank:

Check the solinoid by hot wiring it, then hot wire the starter motor to check that, whichever one fails there ya go.

[AussieE34Touring]

More details please.

Does the car not even try to start? or does it crank?
How long does it crank before starting?
Explain exactly what is happening.

I doubt your aftermarket immobilizer is causing this issue unless it doesnt even try to crank.

Thanks for your reply gman. When warm; car cranks, coughs a bit and sounds like it may start, then keeps cranking for first 2 attempts. I'm confident the car would keep on cranking until the battery died.The car will start immediately on 3rd attempt upon re-inserting the key and twisting. Driving me nut's.

It used start first time on 2nd attempt so it seems something is progressively getting worse over time. Starting on the 2nd attempt lasted for about 6 months, and this 3rd attempt thing has been happening for about 10 weeks.

Cheers,
Chris

[whiskychaser]

Thanks for your reply gman. When warm; car cranks, coughs a bit and sounds like it may start, then keeps cranking for first 2 attempts. I'm confident the car would keep on cranking until the battery died.The car will start immediately on 3rd attempt upon re-inserting the key and twisting. Driving me nut's.

It used start first time on 2nd attempt so it seems something is progressively getting worse over time. Starting on the 2nd attempt lasted for about 6 months, and this 3rd attempt thing has been happening for about 10 weeks.

Cheers,
Chris
Probably a bit late coming back on this but have you tried replacing the fuel pump relay? had similar problems with the honda. would fire up fine when cold but if you stopped for 5 mins it just wouldnt restart. tracked it down to dry joints in the relay-opened up once it got warm. Resoldered and it was fine. Never could quite work out why it didnt give trouble when the engine was running but it certainly solved the problem