Hi guys, been doing a lot of reading but i want to understand something before i drop my tank and replace my fuel pump. Truck is an 04, 5.7 with 110k, driven 300-900 miles a week the past year. No symptoms before it died, no codes now. Last week I got some dumb code about voltage to a parking lamp, but I reset it, nothing now. The day it died I drove 45 minutes on the highway with no issues or symptoms (no prior symptoms either) then ran into McD's to get a burger. When I came back out it wouldn't start. Long story short, no fuel in the rail, I don't hear the fuel pump when I turn the key. I swapped relays for ASD and Pump with good ones. I removed the power from the fuse block, checked for corrosion, cleaned and reassembled. I even swapped batteries since this one seemed a little week from cranking.

Still no fuel......the thing I am unsure of (I am a computer tech, not a mechanic) can I test for power at the relay or something or do I actually have to drop the tank to see if the pump is getting power? I came across several posts where folks put in a new pump and then found it wasn't the problem.

 

Did you try banging on the bottom of the tank and have someone try to start the engine at the same time. Use a rubber mallet.

 

I did, forgot to mention it. Nothing happened, just dry cranking.

 

i would take the plastic cap off the pump relay and have someone hold the contact in on it while you put your ear up to the gas tank, if you dont hear a humming noise you most likely have a bad fuel pump, i dont think its uncommon on the 5.7's.

Oh make sure the key is on while doing this or your wasting your time.

 

I don't hear it, but I would still like to test for voltage before I drop the tank. What's the best way/place to do that? The relay?

Ok, if I pull the relay I have 12v and ground on the big pin slots if that helps.....

Alright, dropped the tank. At the power connection for the tank I have 12v for about 2.5 seconds (trying to prime I would guess) on one set of pins and 10.5v on the other set constant (guage?). Since the pump wasn't doing anything I am replacing the pump tomorrow.

It was the pump....Thanks to those that sent me a couple of tips.

 

[QUOTE=mikehenya;2771701]

on my 03, I can activate the pump by using a paperclip between pins on the relay plug.

Used the lower left and upper right pins.