Please help, not starting, cuts out after 10(ish) seconds?!

[jonb325i]

Hello,

I have a 1988 E reg BMW 325.

For some strange reason, it's recently started to "not start", or even if it does start - it runs sweet for 10-15 seconds, then just cuts out?

Just to let everyone know, I've replaced the spark plug, ignition/ HT leads, the ignition coil, and the distributor cap.

The fuel pump is definately working.

Does anyone have any previous experience to problems like this?

I'll try and answer any more questions you have, to help diagnose this problem.

Thanks

JB

[Globulator]

You've changed all the obvious things.

The fuel pump working does not mean the pressure is right however, a fuel pressure meter would be ideal, but in the absence of one I guess changing the regulator (the black blobby thing with the vacumm lead that restricts the fuel returning to the tank) would be the next thing.

As a short test (but not pleasant) you could try waiting for it to stall and then seeing if any pressure exists by loosening the feed pipe, but you may spray everything with petrol - not good. If it was me I'd try changing the reg/finding a meter. next I think.

Other thoughts are grounding issues with the ECU and engine, and check the engine plug (the big round one near the fusebox) is in good nick regarding the contacts.

[jonb325i]

already tested fuel pressure, and also removed fuel feed from the engine and turned engine over... plenty came out! hehe

the big X5 plug is fine, removed that and had a look - all contacts are beaut - no corrosion etc at all.

we're going along the lines of spark is the problem, as opposed to fuel.

reason being, we removed plug number 1, put it on HT lead at put it on bare metal, car started but then it stopped firing then the car died.

hence the replacment of plugs. leads. coil, then we traced power getting into dizzy, but not coming out of dizzy (at the end of the plug), so we replaced the dizzy.

power now getting all the way to the plug, but still this intermitant fault.

could be immobilisor kicking in every so often, seems to die almost exactly 12 seconds after its started everytime

[Globulator]

If you can see this much detail you may want to put a 12volt LED across the LT (Low tension) side of the coil - LEDs are very fast and it will tell you when the engine dies ... if the LT side has died or not.
Use a 12 volt one - not a regular LED.

[E30BeemerLad]

isn't there some sort of relay that powers the fuel pump during "cranking" of the engine so you get fuel through, but once the key returns to the normal position the pump then dies so starves it of fuel unless the relay or pump are working correctly?

If you managed to search for a wonderful thread by Brianmoooore from his holiday exploits last year whilst trying to start his e30 which also had a gas conversion, there will be some useful info in there.

[Globulator]

Perhaps you can rig up a pilot lamp to the fuel pump power wires (probably easier said than done - but they may be accessible under the rear seat) and just check it stays on after you let go of the starter and the engine runs.