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Fuel Technical ? 4.3L

09-23-2007, 11:48 PM
Well I will start out by telling you the symptoms. this truck is not daily driven and now that i have went back to start it up it is having fuel issues.
When i turn the key to ACC. once in a while the pump will prim. After that there is no chance it will prime
I can manually put power to the pump it is still good. I have checked all grounds relay battery pump, not ecm yet but i can bet it is a great ground.
On the firewall there are 4 relays mounted, the hanes manual says that 3 of them are for the ac which is incorrect cause i went threw them and put individual power to certian wires for running lights and other stuff to come on. so i think one of them is ac one is fuel pump one is oil something. and other running lights.
I am not 100% positive which one is the fuel pump relay but there is only one 5 wire relay and the manual says it has 5 wires none of which is color coded according to the book.
when the ignition is on the relay is getting no acc power. Is it suppose to be a 2 second momentary or ?
this is where im stuped.

i have read alot of forums on this and cannon figure what it is. I have been told it could be a bad computer or ignition module.

How could I test the 2?

09-24-2007, 08:20 AM
Welcome to AF

What year?

When it acts up do you have spark to more than one spark plug.

Does the fuel pump run when cranking the engine?

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