1988 BMW 325 Replaced Fuel pump and pump relay, still not s

STOUTIE

MEMBER
1988 BMW 325

Electrical problem
1988 BMW 325 6 cyl All Wheel Drive Manual 177K miles

I replaced the fuel pump in my girlfriends 88' BMW 325ix because that is what one of our overpriced shops quoted. When I would turn the key on, there was no "hum" from a working fuel pump. I tested the relay, which had power when the 30 and 87 circuits were jumped, but no power to the fuel pump, and still not working. While it was jumped, the pump would work. I was informed today that the tow truck driver who took her car to the shop tried to jump it first, and that this is usually a no-no. I wonder what I need to test next. Can someone help me figure that out? Thank you very much

ryan

4 Replies

DOCHAGERTY

MECHANIC
9,601 POSTS

So there is a no start issue here, right. And some shop said it was the fuel pump, so you changed it, now it wont start. When did this no start issue first happen? What was it at the shop for?

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Tuesday, March 17th, 2009 AT 2:35 PM

JAMES W.

MECHANIC
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Ryan, it could be any # of things causing the problem. Let's start with the simple ones.
All fuses good, YES?
Do you have spark, YES?
Do you have injector pulse? You can check pulse with a regular "incandesent" test light connected to the injector plug terminals. You can't use a a neon, LED or a digital volt/ohm meter. They won't respond fast enough. Do the pulse test with vehicle cranking.
Jumping a "Beemer" is never a good idea. The results of the above tests will confirm any damage and give us a diagnostic direction. 30 and 87 terms are, power in/out for the fuel pump. The other 2 are relay control that comes from the computer.
I've attached some diagrams. Do the tests and get back to us.
EDIT; Our posting system doesn't support PDF files. Only "jpeg" and they don't transfer well due to the compression required for full wiring diagrams. I can send them via your email adress if you'll send it back.

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Tuesday, March 17th, 2009 AT 2:59 PM

STOUTIE

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2 POSTS

To answer both questions, the car was towed to a shop because it would not start one night, and was diagnosed with a faulty pump. We "drove" away from the shop, and replaced the pump. Parked the car and replaced the pump, now it won't start and the pump won't run on its own without having the socket beneath the fuel pump relay jumped from 30 to 87. I have checked the fuses, I don't know how to check for spark or injector pulse. My email is adviserryan@aim. Com for the schematics you were going to send

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Thursday, March 19th, 2009 AT 3:35 AM

JAMES W.

MECHANIC
2,394 POSTS

To check for spark; Pull one plug wire off any spark plug. Insert an ordinary "phillips head screwdriver into the plub boot and lay anywhere on the engine so the driver shaft is approximately 3/8 to 1/2 inch off the engine. No part of the bare shaft can be touching the engine. Have someone crank the motor and watch the driver shaft for spark jumping to the engine(ground). Spark yes/no?
Injector pulse; Pull the connector off any fuel injector. With a regular "incandecent" voltage test light, connect between the 2 terminals of the injector connector. Again, have someone crank the engine. You're looking for a "blinking" of the test light. Let me know what you find.

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Thursday, March 19th, 2009 AT 6:36 PM