cranks but not starting. Ideas please.

[spasticone]

Ok. This is my brother-in-laws car. 90 lumina 3.1.
All of his work up untill this, has been done by his mechanic. it's had lots of new parts including 4, yes 4 ecms... Last week it had a fuel pump, and when installed it burned out the pump. So the guy threw in a new module AND a new pump and it was ok for a week. now it's stuck in the middle of my driveway. It turns over like crazy but won't start. When I turn on the key, I can feel the relay in the little "Fuel pump relay box" click, but as of yet, no fuel pump whine. I fould online that you can bridge terminal 87a and 30 on that relay and the pump should run, but it doesn't seem to work. Oh yeah, It throws a code 54. What's "low voltage in circuit'? What next???? Please help me out as I need my driveway and he needs his car. I'm reletively competant so throw some tests for the fuel system or ecm my way. Thanks in advance.

[tblake]

ok, the fact that you went though 4 ecm's tells me that something is shorting them out. could be a number of things. look for bad wiring, melted wires, anything, you say you dont hear the pump. Did you by chance blow the fuel pump fuse? I myself would start by checking all the wiring going to the fuel pump, as that might be your problem. Do these cars have a fuel pump inertia shut off valve? Just a thought. I helped a buddy of mine replace a fual pump in his escort because ("it just stalled out and wouldnt start when I went over these bumps"). We got the new pump in, and still nothing, it wouldnt buzz, so i read the manual, turns out there is a safety switch in his trunk that got tripped by hitting all those bumps. He clicked the switch, and started the car right up. He did keep the new fuel pump though. moral of the story, check the easy, obvious, cheap things first, then start replacing parts. Good luck

[spasticone]

Does anyone know if I can jumper a hot to a post on the fuel pump relay to test the circuit after the relay to the pump. If I supply direct power and it won't run.... Another pump. I def. agree with the something is frying things idea, but I don't see anything too obvious. Any tests for the fuel pump circuit would be very much appreciated. Thanks for the input.

[meuhus]

Originally Posted by spasticone

Does anyone know if I can jumper a hot to a post on the fuel pump relay to test the circuit after the relay to the pump. If I supply direct power and it won't run.... Another pump. I def. agree with the something is frying things idea, but I don't see anything too obvious. Any tests for the fuel pump circuit would be very much appreciated. Thanks for the input.

there should be a fuel pump test terminal lead near the relay box area if you supply 12 volts to it it should turn on the pump
get a wire diagram to help locate and dermine wires and colors
yes you can jumper at the relay connection test for the one that has bat. volt
jumper that one to the one that goes to the fuel pump fuel pump should run
if the pump doesn't run with either one of these tests and the pump is good then its in the wiring to the pump
you could also find the conection at the pump and supply 12volt to the hot side of the terminal with a wire from the battery and ground the side that needs to grounded at the terminal
if the pump runs its the wiring

i had a leaking oil pressure sender/fuel pump switch that was leaking oil.
the oil i guess completed the conection or some thing because when i shut the car off it would still run (the fuel pump would still be running)
changed sender and fixed leaking and the running on fuel pump