97 Z71 fuel pump intermittent

When I first try to turn over the engine, the fuel pump does not always engage. I have to listen for the pump running sound and then it will start. If I do not hear the pump running, then I have to turn the key all the way off and back on untill I get the pump to engage. Any ideas??

When I first try to turn over the engine, the fuel pump does not always engage. I have to listen for the pump running sound and then it will start. If I do not hear the pump running, then I have to turn the key all the way off and back on untill I get the pump to engage. Any ideas??

What engine?
What mileage?

Good 12 volts to and threw fuel pump relay?
When it will not run are you getting good spark to plugs?
Any check engine lights?

Things just got worse. I have a 5.7 vortec with 150,000 miles on it and there are no check engine light on. I replaced the Fuel pump relay and now the fuel pump will not work at all. What could have happened?:uhoh:

Does it have spark to more than one spark plug?
12 volt power going to fuel pump relay?
12 volt power out of relay on gray wire on 3 second prime up with key on?

Does the fuel pump run on 3 second prime up?

Take a rubber mallet and bang on the gas tank while someone tries to crank it. I paid $60 to a wrecker driver for this "trick" It is a sure sign of a bad fuel pump motor, banging makes it hit on a better part of the armature.

Truck is fixed!!! The fuel pump was bad, and the wire from the pump to the wiring harness was burnt. This probably was why it was intermittent.