Truck Repair: wont start sometimes, chevy silverado 4x4, chevy silverado

Question
I have a 1996 Chevy Silverado 4x4 5.7 VORTEC and sometimes it won't start. I have cleaned the terminals and sometimes after it sits it will start. It has stopped on me while driving and I used a rubber mallet and hit the bottom of the fuel tank because I couldn't hear the pump run when I tried to restart it. What would you think it is or what to do?

Thank You

Answer
Hi Mike,
You open up a lot of possibilities, but don't really tell me all I need to know.
You say it won't start...does that mean it cranks over, but won't start, or does that mean it won't do anything?
If it cranks over, the battery terminals wouldn't be the cause, since they are carrying the power to crank it.

You use a mallet...but does that make it start and run then, or do you still have to wait?

If it cranks over, but won't start, and you can't hear the pump running, but hit it with a mallet, causing the pump to run, which in turn allows the truck to start, then I would say the fuel pump itself, or the wires connecting it are the problem.
You could start by making sure the ground wire near the tank is clean where it makes contact with the frame, and tight. If it is, and the harness connector is clean and tight, I would say you need to remove the pump from the tank.

I have done it both ways...drop the tank, and remove the bed, just moving it rearward about two feet to gain access, and unless the bed bolts are real rusty, that is a little easier than dropping the tank, especially if the tank has a bunch of fuel in it.

When you remove the tank unit from the top of the tank, which is the pump and the gauge sending unit, first check the wires inside, which go from the top of the tank unit, to the pump. I have seen them be loose where the rivets connect them to the top of the tank unit, and that be the complete problem, and repairing that intermittently loose connection might fix the problem. I saw some so loose that they were generating enough heat to melt the plastic, causing them to become looser still.

I would probably replace the pump anyway if it never has been replaced, but be sure to check those wire connections, or you could be going back in there again, even with a new pump.

Van