1987, 320i, randomly stalling issues / fuel pump runs intermittently

[Mroku96]

Hiya
I’ve been having a wired issue with my e30 lately, hoping someone will be able to point me in the right direction.

So my bmw is a 1987, 320i the preface lift model. The car has been randomly cutting out / stalling when driving ( no matter if it’s rainy or hot )
When the vehicle cuts out, it cranks but doesn’t start. I can’t hear the fuel pump priming, nor the fuel pump relay clicking (when cranking) After 30 secs the vehicle starts just fine (Fuel pump priming) This can happen 2-3 times in a row, and after that the car runs absolutely fine. It seems that the fuel pump relay or fuel pump is overheating 🤔 and tripping out.
What can cause the fuel pump relay to trip out, is it a bad fuel pump ? Fuel pump relay? Or is it the crankshaft sensor ( don’t think so as the fuel relay shouldn’t be affected by the crank shaft sensor )
I’ve previously fitted :
new ignition coil + dizzy + rotor arm + HT leads
new fuel pump ( Boshe) / tank / hoses

[jbontke]

I am not very familiar with the 320i. I believe that when the DME sees the crank sensor pulses, it turns the fuel pump on. Anyone know this for sure?

When the car is cranking, but not starting, test for spark at the HT lead to ground. I typically use a screwdriver to see the spark jump to the valve cover. If you have spark, then spray carb cleaner in the fuel pressure regulator vacuum port, spraying into the engine. If it trys to start, it's definitely a fuel pressure issue.

[It's Soda Not Pop]

Next time it cuts off or won't start while cranking. Reach under the rear bench and jiggle the connector on the fuel pump. See if the car will start after that. Or you can jump pin 11 and 14 in the Diag plug under the hood.

[Mroku96]

The problem is that when the car failes to start I don’t have enough time to start any diagnostic as the fault goes away very quickly.
On the preface lift m20, where is the DME relay located, I have only 1 relay on the wing bracket, and that the fuel pump relay. Is the DME relay in the engine fuse box ?

[82eye]

try having a look over at e30 zone. you're running a model and set up we never got in north america. i think your relay locations may be different. on some rhd it is on the passenger side, on others it can be on the firewall.

[Mroku96]

Ahh I see, no worries thanks 👍