View Full Version : GMC 3/4 ton fuel pump?????

02-14-2008, 01:14 AM
After putting gas in my truck a few months ago, I turned the key and the truck wouldn't start! Luckily a friend of mine who is much more mechanicaly inclined than I was there to help. He banged on the gas tank with a hammer and my truck started right up. He told me my fuel pump was going bad and if it happened again to bang on it a few times and start it up. It happened 4 or 5 times today and after banging on it for a few she started right up!
I plan on getting it into the shop soon, but is this "band-aid" fix OK for now? How long before it won't start period? Does this sound like a fuel pump issue? Any ideas on how much this will cost? Money is pretty tight right now and it seems like every month I'm putting $ in this dang truck! Any insight would be appreciated! Thanks!

I have also noticed a buzzing sound sometimes when I get out of the truck!

02-14-2008, 01:21 AM
Sorry! Meant to post in the mechanics and repair forum.

02-14-2008, 02:02 AM
You need to find out if you have to pull the tank...
I would guess you do but some cars have an access hole from the top.

The pump itself run anywhere from 40-50 to 2-300, there's just no telling, then the labor. As for how long it will run as-is, your guess is as good as mine, one day it won't start no more, could be a year down the road, could be tomorrow.

If you know what you're doing I've seen a guy hook one up under the hood, spliced it in and that worked, aftermarket.

02-14-2008, 08:28 AM
The humming seems to by typical of GM's electric fuel pump.

If I recall correctly you will have to drop the fuel tank. A transmission jack would make the job easier.

Again this is from memory, I don't have my repair manual at the handy.

02-14-2008, 11:06 AM
Happens quit often on GM trucks, shops will charge a lot to do it. If money is tight I would attempt it myself. Do you run your truck a lot on the lower half of the tank? If you do that can cause premature failure on pumps, its the fuel that cools down the pump. I have also herd of people mixing a little two stroke oil with there gas to get a little life out of there pump, I have never done it and it might be to late.

02-14-2008, 01:05 PM
definitely sounds like your pump. Ive found good ones on ebay for $120. depending on the engine/tank it could run as much as $300 at the parts store. Basically you need to drop the tank after disconnecting the lines and wiring. The new one goes in and you reinstall. Oh and you make sure the tank is clean while you have it open. The pump isnt the big labor issue its the PITA that is dropping the tank. Mostly corroded lines, fittings, and bolts. It shouldnt take them more than 2 hours. Ive heard of people cutting the floor out of the bed to easily change it, but aside from the hole you can damage the wiring or lines if your not real careful. If your not mechanical just pay someone.

02-14-2008, 01:21 PM
You could take the box loose and jack it up enough to get at it rather than screwing around dropping the tank.

Sydenstricker Landscaping
02-14-2008, 03:05 PM
It is a realtively easy job to do. Get a few of your buddies over and just unbolt and move the bed. It is a heck of a lot easier than dropping the tank. Plus you dont have to lay on the ground and try to bust rusty bolts loose on the tank, etc. If you do choose to drop the tank, make sure it is near empty or empty. Gas weighs roughly 7 pounds per gallon. So it can get heavy real quick!!!

lawnboy dan
02-14-2008, 09:34 PM
i totally agree! i have done this job both ways and taking off the bed is easier than droping the tank

02-14-2008, 11:46 PM
It would also make a good time to fix other things like, throwing on a new pair of shocks.

02-15-2008, 12:50 AM
Try $700-$800 for a gm fuel pump, thats what my old man paid for his in a Tahoe. Yes you have drop the tank.

Chop Stuff Up
02-15-2008, 08:36 AM
I did it by pulling the tank down. My truck was a chevy. Its just a couple bolts but they can be rusty and hard to loosen. I used air tools. I used a jack and jackstands to support the tank. After you pull the tank you unplug the fuel pump wires and there's a metal ring around the pump holding it in. You turn it counter clockwise until it loosens and your fuel pump pulls right out. It'll be attached to a float mechanism and if I recall correctly it unscrews from that. When you get the new pump you need to get a filter thingy also but I forget what it is called. It goes right on the pump. When I emptied my tank it still had 3 gallons after the dash read it as empty. 3 gallon reserve maybe?

02-15-2008, 08:39 AM
Do it before you need a tow.

02-15-2008, 04:37 PM
Thank you everyone! It is beeing worked on right now. $482 - includes parts and labor. $40 to have it towed 1\2 mile. I waited i day too long to get it in. Could not get it to start today.