i helped a friend of mine remove the fuel tank and replace the fuel pump and also filter on his truck. and tried to start it but it would not. First,prior to replacement,his fuel pump would make a buzz noise indicating its on when your turn/start the truck.(its a normal noise you hear)but obviously on later time his pump went out and needed to be replaced.did some power troubleshooting, we were not getting enough power from the relay to the pump(via wiring harness connection), so we replaced the fuel pumprelay(big square fuse looking thing)hoping it was the source of weak powerbut still would not start.everytime he tried to start it the pump would not kick on.meaning also that he cannot hear thebuzzing noise that indicatesthe pumpis on. any suggestions/ inputsis greatlyappreciated. its the onlyvehicle he has. thanks again

 

are you getting power at the relay? are you getting power at the fuel pump? inspect all the wiring and check with a DMM if you have one.

 

What kind of vehicle are we talking about here? Recently, my father's '94 GMC 2500 pickup was having similar issues. The pump quit. He replaced it before I could get a chance to help him. The pump wasn't the problem, the fuse had blown, caused by a short in the main power lead to the fuel pump. We had to disassemble the wiring from the pump to the fuse to find the frayed section and repair it.

 

its a '99 silverado, his fuse and the wirings were good.i'm not much of an electrician but he is and he was not getting enough juice.from the fuel pump relay to the wire connectors that leads to the tank,his reading were .02 volts dc and on the fuel pump relay inside the main fuse box he said his not getting enough juice either thats why he replaced itthinking it could be it,but it was not. he is still troubleshooting his truck.

 

As with any relay, you can use a jumper in place of the relay to supply full voltage to the pump to rule out the relay. If that doesn't work, then he's definitely got a wiring problem.