E30 won't start! help! '86325es

[ej207]

hey everybody, got a 1986 325es 2.7 inline 6

1)How exactly do I check if the fuel pump is working if I removed it? what if it is still attached underneath the car?

2)How to check fuel pressure regulator?

'86 325es seems to only start intermittently. Car cranks but won't start. However, every now and then it seems to start. and it looks like it starts after the car has gotten some rest after cranking it a bunch of times.

Today I've check the fuel pump relay by jumping pin#80 and 37 to see if I can hear the fuel pump working but didn't hear anything. Right after I plugged the relay back in and then start the car and it works! For about 3-5 seconds of run time. Also checked the wiring to the in tank transfer pump with a multimeter and that seems fine. I also checked the wiring to the external fuel pump(near rear driver's wheel) and it reads 12v.

How do I know my main fuel pump is actually out? It seems like if I give the car a good amount of rest time inbetween tries to start the car, it will work. But if I try to start the car again it won't start.

Possible that the main fuel pump has overheated and will only work with rest?
I want to order a new main fuel pump, but the fact that the car starts after some rest tells me it might be something else..


Thanks!

[ej207]

Ok some updates:

Tested the under car fuel pump and the in tank transfer pump and seeing if they would work if I connected the car's battery(12v source) to it. Connected it to the car's battery and both the fuel pump and the transfer pump didn't make any noise of any sort.

Which points out that both the fuel pump and transfer pump are dead, but how come the car is able to start every now and then?

[jlevie]

You may not hear the transfer pump, but with power jumped to the pumps you ought feel vibration from them.

If there is sufficient fuel in the tank, the car will run on just the high pressure pump. But if it is intermittent, that would explain the occasional start failures. Or if the ground is bad (on the left fender well behind the rear seat) that would also explain it.

[ej207]

Just an update to everyone that might be running into the same problem as me, it was a dead transfer pump and dead main fuel pump. Fixed it with swapping in a Chevy vega fuel pump as the transfer($20-30 instead of the oem $170+) and dropped in a new bosch main fuel pump. For anyone wondering about the transfer pump, it's a little bit noisier than the oem one, but once you're moving the sound is barely noticeable unless you drive in silence lol