Expert: Sean Halliday - 10/18/2008

Question
I turn the key to the on position and test for power at the pump and come up with nothing.  Could this be a relay and if so where is it located?  Or is it possibly a corroded wire? Any help would be appreciated.  It's getting cold in Michigan and don't wanna be crawling on the ground when the real winter hits.

Answer
It could be the relay or wiring/fuse.You may not get power unless you crank the engine as the pump doesnt work unless the engines running.Do you have an inertia switch on this vehicle?Make sure its switched to on.You will need to get someone to turn the key as you check for power to the pump.Does this vehicle have 2 tanks?If i remember correctly this truck will have 2 pumps?Inner and outboard.As for the relay it will be in the main fuse box relay compartment and will be shown in your handbook.If you cannot find it,simply google it and you will see what it looks like(small black).Rock auto.com have this part and it also has a picture with part#.On this truck,the fuel pump will run for 5 secs for initial start up as the system puts enough fuel in for ignition then once the engine fires up the main pump/s takes over.So,you need to check for power to the relay and fuse and also coming from the relay when the key is turned to position 2.If no power coming from the relay then replace the relay,if power is coming from the relay then a faulty pump/s is suspected.Dont forget to check the fuse for the pump and 12 volts to the circuit.If you have only 1 pump in the tank the same procedure is followed.