Fuel pump cutout

NEIL MYBURGH

MEMBER
1994 BMW 525I
6 CYL
RWD
AUTOMATIC
218,000 MILES

Car cuts out and refuse to start. Speedometer reads 0. Third fuel pump. When car is on checked the positive and negative cables to fuel pump. No spark, no power. When key turned to start there is power. But not when key is turned to on. Pumps work fine when connected to battery.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Hey Neil,

It sounds like you have a problem with the fuel pump relay, here are some guides and a wiring diagram of the fuel pump circuit so you can do some testing to figure out the problem.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please run this test and get back to us so we can continue helping you.

Best, Ken

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Monday, March 27th, 2017 AT 9:06 PM

NEIL MYBURGH

MEMBER
5 POSTS
1994 BMW 525I
6 CYL
RWD
AUTOMATIC
250,000 MILES

Replaced fuel pump twice, plus filter, cleaned tank. Car cranks but no fuel to engine. When checking power to pump, no power when car is on but power when starting, no fuel going through. Started well drove for two weeks then cuts out. When testing pump from battery pump runs continuously. When key is in start mode, car cranks but the speedo needle don't move.

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Friday, March 31st, 2017 AT 1:25 PM (Merged)

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Hello,

It sounds like it could be a crankshaft angle sensor that is causing the problem, can you run the codes to see if there are any?

https://www.2carpros.com/articles/bmw-obd1-1995-and-earlier-code-definitions-and-retrieval-procedure

Please let us know what happens.

Best, Ken

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Friday, March 31st, 2017 AT 1:27 PM