Mechanics

NO POWER TO FUEL PUMP

1987 Chevrolet Silverado • 89,000 miles

I just replaced fuel pump cause had no power lucky I did cause strainer was bad but still no power to it but when I run jumper from fuel relay to 12 volts the pump works it does have dual tanks but the passenger side doesnt work theres not any fuse links on power wire by battery only by alternator and down by starter both are good check fuel relay and its good. Did separate the fuse box from outer but dont see any fuse links there either. Have any idea on where else I can check?
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Fabian19720
August 21, 2012.



Did you test the fuel pump relay? If relay is good, it is not being energised, either no power supply from ECM or it is not being grounded.

Does the Dark Green/White wire at fuel pump relay has battery voltage when ignition is turned on and while cranking?


KHLow2008
Aug 21, 2012.
Not really sure if I check it and I dont have voltage there where do I go from there as I already tried changing ecm and no difference


Tiny
Fabian19720
Aug 21, 2012.
What is your vehicle specific model? R10, R20 etc?


KHLow2008
Aug 21, 2012.
R10 2-wheel drive


Tiny
Fabian19720
Aug 21, 2012.
At the ECM, check terminal A1 for battery voltage with ignition turned on. This would only last a couple of seconds as the fuel pump primes. Crank the engine and if battery voltage is available, you have a broken connection between the ECM and the relay.


KHLow2008
Aug 21, 2012.
There are 5 terminals for the fuel pump relay, do you have battery voltage at the Tan/White wire? If no, check the oil pressure switch.


KHLow2008
Aug 21, 2012.
Do u have the wiring diagram for the fuel system in my truck that u can post for me


Tiny
Fabian19720
Aug 21, 2012.
Here you are. They are too small so I split them up. See if you can print them out and join together for a clearer picture.


KHLow2008
Aug 21, 2012.
Ok on my truck on same bracket as fuel relay theres another relay there with different number but nothing plugged into it do u have any idea on what its there for


Tiny
Fabian19720
Aug 21, 2012.
I read on another website that some trucks cam out with a 20 second relay for harder starting trucks not sure if thats what it is or not


Tiny
Fabian19720
Aug 21, 2012.
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