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Tim West
Tim West, ASE Certified Technician
Category: BMW
Satisfied Customers: 4638
Experience:  ASE certified service manager BFRC - Electrical Specialist
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95 740I: FUEL PUMP..THE CHANGE THE CAR STARTS AND RUNS ROUGH..OFF.

Customer Question

I HAVE A 95 740I THAT WOULD NOT START, THE FUEL PUMP WAS NOT COMING ON SO I CHANGED IT. ATER THE CHANGE THE CAR STARTS AND RUNS ROUGH FOR ABOUT 3 SECS AND SHUTS OFF. WHILE ITS SHUTING DOWN AND AM GIVING IT GAS IT SOUNDS LIKE AN AFTER MARKET INTAKE(THAT RUMBLING SOUND) AND SHUTS DOWN.
Submitted: 8 years ago.
Category: BMW
Expert:  Tim West replied 8 years ago.
Thanks for choosing JA,

Check fuse 23 - it should get battery voltage from the fuel pump relay with the engine cranking or running.

If the fuse is OK and is hot cranking, check for power and ground at the fuel pump. The Green/Violet wire should have battery voltage and the Brown wire should be ground.

If fuse 23 does not get hot, locate the fuel pump relay, mounted in the electronics box at the passenger's side rear of the engine compartment. Check for constant battery voltage at terminal 30 (Red wire), switched battery voltage at terminal 86 (Red/White), ground during cranking from the Motronic control unit at terminal 85 (Brown/Green), and see that if the relay is pulled out of its socket and a jumper wire is put between the sockets for pins 30 & 87 of the relay, fuse 23 gets battery voltage and the pump runs.
Customer: replied 8 years ago.

when using regular 12v tester i get no power at the pump , but when use the snap on probe there is power at the pump how much voltage is the pump

 

 

 

 

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Expert:  Tim West replied 8 years ago.
What wire are you testing?
Expert:  Tim West replied 8 years ago.
What wire are you testing?

Customer: replied 8 years ago.

I tested them all

no power not even from the violet1

but this occurs with the 12 volt tester withe probe it seems fine

 

Customer: replied 8 years ago.
You there?
Expert:  Tim West replied 8 years ago.
What reading are you getting with the probe?

You verify it's getting power. What about ground? Jumper the ground wire to a known good ground source. You don't have to check the pump directly, you should test the relay. If the relay isnt getting power, the pump definately isnt.
Customer: replied 8 years ago.
My probe doesnt have a meter pardon my lack of tools but am working on it in my backyard. It didnt start at all before i changed the pump but now its starting it just wont stay running so am assuming the pump now works but there is another problem
Expert:  Tim West replied 8 years ago.
Okay, keep in mind the fuel pump can only get power while the key is on.
Run a wire past the relay, bypass the relay completely.


I will be back in the morning.

graphic
Customer: replied 8 years ago.
Relist: I still need help.
MY 95 740I KEEPS FLOODING, THE FUEL WONT BURN
I USE93 OCTANE, CHANGED THE PLUGS FAS FILTER BUT IT KEEPS FLOODING