91 535i fuel pump problem - BMW Forum

Panel Beater · 04-13-2010, 08:05 PM

Hi guys

I just went to pull my 535 out of winter storage, and got no response from the fuel pump. Fuse was okay, so pulled the pump and bench ran it, it's okay. Removed the relay and jumped the appropriate terminals, pump ran fine. Stuck a new relay in , still no go. Is there a fuel pressure switch or any other sensor that would tell(activate the relay) the pump to run or stop?
Any help greatly appreciated !!!!

Thanks,
Doug

bimmer35i · 04-14-2010, 11:01 AM

Hey man...
we will ask around about your problem.. but in the meantime could you describe
the pump removal steps... cause we just dropped the gas tank off our 735i
parts car and removed the bolt plate at top side of tank but are unsure how to
detatch the pump down inside the tank... Thanks DBB

Panel Beater · 04-14-2010, 01:19 PM

Hi there
With the tank out, with the top plate loose gently pull out the fuel level sending unit. The return and supply fuel lines will run down to the pump, so do not heave on them. Once the sending unit is above the tank you will look down into the hole and see the pump mounted in rubber. On the right side of the pump on the plastic collar you will see a release tab , squeeze it to release the pump and hard plastic mount from the rubber insulator

DonJ · 04-17-2010, 07:42 PM

Quote:

Originally Posted by Panel Beater

Hi guys

I just went to pull my 535 out of winter storage, and got no response from the fuel pump. Fuse was okay, so pulled the pump and bench ran it, it's okay. Removed the relay and jumped the appropriate terminals, pump ran fine. Stuck a new relay in , still no go. Is there a fuel pressure switch or any other sensor that would tell(activate the relay) the pump to run or stop?
Any help greatly appreciated !!!!

Thanks,
Doug

Did you check the crank position sensor?
How is the fuel filter - is it time to replace it?

Panel Beater · 04-19-2010, 08:42 AM

Hi Don
I did check the crank sensor, I believe it calls for 540 Ohms give or take 10%. I read 495. I also did a voltage check to the sensor and got extremely close to the required 5 volts. I also did a continuity on the ground supply wire from the motronic to the fuel relay. All grounds for the ECU are also O.K.
Is there an enertia switch in this car???
Thanks
P.S. When I manually ground the relay, the car functions perfectly !!

DonJ · 04-19-2010, 10:08 PM

Certain models have an inertia switch but I'm not sure which ones, I haven't read up on those so I'm not sure.