QuestionI have a 1994 BMW 325i and I am not getting power to the fuel pump and when I add external power to it and it runs something is still not letting the fuel go into the cylinders. I have check the fuel pump and it works fine with an external battery hooked directly to it. The wires to the fuel pump are not hot but the wires to the gas level sending unit are hot and working. I have checked the fuel pump fuse and it is okay and has power to it, I have check the fuel pump relay and it appears to be okay and has power to it. Can you tell what else I should check? Is it possibly a main computer control problem with the vehicle. Can you give some circuit checks I should make that can help me isolate the problem. As I stated even when the fuel pump is turned on using another power source it appears when I try to start the vehicle that something is keeping the fuel from getting to the cylinders. Thanks,
George
AnswerA couple of questions for clarity: I think you say
- You have power to the fuse
- You have power to the relay
- You DON'T have power to the fuel pump.
If thats the case, there is a problem just upstream (up circuit) from the fuel pump. A bad wire, a dirty connector, etc.
You say that the fuel pump works with external power, but seems to be blocked when trying to get fuel to the cylinders. did you test the fuel pump by having it pump gas through the hose? If not, may be a faulty pump.
If it pumps through the line, does it pump out at the fuel filter if you disconnect it there? Do you have dirty injectors, or a pinched fuel line somewhere?
You've done a good job of chasing it this far. you're close......take it one more step, and good luck.
