Fuel Pressure Testing Question

[av8r]

Hi all,
Well after battling the stall and cut out problem i finally did a test of the fuel pressure. The guage bounces from 20psi to 30psi and will sometimes go to 40 psi. I tried pinching the return line by the Regulator and it just kept pulsing and then finally went to zero psi and of course stalled. It would indicate to me that it is not picking upo fuel at all times. Is there some sort of pick up screen on the pump or is it just that the pump is going south? Another test without the car running was to get 12v to fuse 23 and it would jump up then go to zero, it never held any pressure. I guess my question is should i try and look at the Pump or just replace it?
Chris
95 530i m60, 1975 cessna 172m

[bbig119]

Had a similar problem back in December and January. In short here is what I suggest-- jump the fuel pump relay and see what happens with the pressure. In my case when I had the access cover removed and listened to the fuel pump it sounded like intermittant squirting.

In fact when the car was idling(which it did poorly) it appeared that the car would just about stall out and then I'd hear a squirt from the pump and the engine would surge again. This cycle happened every few seconds and eventually ended with a stall. I replaced the fuel pump and that totally fixed the problem. I suppose its possible that the screen is clogged, but if the pump has never been replaced its very reasonable to for it to be dying slowly of old age.

You can search and find out all the symptoms and issues I had trying to diagnose the fuel pump. The repair is simple-- took about an hour after I cyponed the fuel down to about 1/3 tank.

Hope that helps.

[av8r]

Thanks for the reply. I just had to try and put the pump back in with no filter. Spot on 50psi with a surge when the trottle is advanced. So its off to the stealer tommorrow and pick up a new screen.
thanks
Chris