Help required with 740 cold start problem...

[ScoobyD]

Hi there, just wondering/hoping that there may be someone out there that could help with a problem I have with my trusty 1988 740 Estate!!

It starts first time, but when the temperature gauge reaches middway between cold and normal the engine cuts out. It will not restart immediately but will do so if left for a short time (approx 5 minutes) but then will just suddenly cut out again. I continue to have this cutting out problem until I manage to get the temperature to normal operation, once normal has finally been acheived the car runs perfectly without any further problems. I've had the car for 15 years now(!) and it's never let me down in this way before.

I look forward to hearing anyones opinions or finding out if this is a common thing on these engines?

Many thanks in advance...

[Skyedriver]

Probably not much help but my 740 and 940 will not restart if you stall them (or they don't run cleanly from starting). Think it's a safety feature in case of accident but when you pul out of the gate and it cuts out on a blind bend and won't restart....
Check around for an electrical connection on the fuel system

[Tunku]

Could be the fuel pump relay with a dry joint. Common problem on the 740. Either open it up and solder the connections or swap it out. There is another relay in the car you can swap over, dit I'm damded if I can remember which one at the moment.

[ScoobyD]

Thanks very much for the advice. I checked out the fuel pump relay and indeed there were dry joints, also some burning on the wiring. After replacing the relay and damaged wiring on Wednesday I have not experienced the problem again so far. The car has been OK for the last 2 days so hopefully this has solved the problem.
Many thanks again for the help.

[ScoobyD]

Bad news.. The problem has returned! Cut out on me this morning just as the temp gauge was half way between cold and normal therefore exact same problem as before.

Further help required please.

[Tunku]

ScoobyD said:

Bad news.. The problem has returned! Cut out on me this morning just as the temp gauge was half way between cold and normal therefore exact same problem as before.

Further help required please.

Bad luck there ! Is the replacement relay new? Also check the fuse box under the ashtray to see if there is any overheat damage to the fuse holder for the relay.