Mechanics

FUEL PUMP

1996 GMC C2500

Computer problem
1996 GMC C2500 V8 Two Wheel Drive Automatic 189000 miles

My truck turns over but will not run. I know the fuel pump is not turning on when I turn the key on, but it is good as I changed it and found the old one is good also. I hook the fuel pump up directly to a battery and it runs and the truck will start and run fine. After is sits for a day or so I go back and the truck will not run again because the fuel pump is not turning on. It seams there is a switch that trips or safty feature keeping it from working, but if I bypass it and start the engine it will work for several days, (not hooked up directly, I un hook it from the direct wire) turning on and off the engine and then out of the blue the fuel pump stops working, and there is no power to the fuel pump as I have tested it at the tank. I understand there is no safty switch and there is a computer that tells the fuel pump to work or not. The error code is 102 MAF, Low flow, will this stop the fuel pump? Where is the reset button?
I already donated $10.00 ealier and though it was for this question, so I am only putting $1.00 on this one.
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Gregevans
March 21, 2010.




Hello gregevans

The simplest thing to do is to reset the code and see if it comes back. Then start with the cheapest, easiest repair procedures:

* Verify that the Mass Air Flow Sensor wiring is connected properly and that there are no broken / frayed wires.
* Inspect for any air leaks near the MAF sensor.
* Take the MAF out and clean it using a spray cleaner such as brake cleaner or electrical contact cleaner. Be gentle with the sensor.
* Check the voltage of the MAF sensor
The fuel pump and the MAF sensor are not related.
Check the fuel pump relay and its ground.
check fuel pump prime connector(see diagram).
Check the hot fuel module ground, as fuel pump gets it power from the relay through that module, make sure it has good ground.
check connector between FP relay ,Hot fuel module and fuel sensor/oil pressure.(see diagram in your email for details)


http://www.2carpros.com/forum/automotive_pictures/46384_0996b43f802424c7_5.jpg


Tiny
Mathiaso
Mar 21, 2010.


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