fuel pump down on my 1996 GMC dually...

Not open for further replies.
Aug 4, 2004
wytheville, va
I've pretty much determined that my fuel pump has quit on my '96 GMC ton truck.

I've checked the voltage sources, and they appear in order... the main 12V source, as well as the 2 second 12V pulse that is supposed to occur when you first turn on the key. All that is good. The fuel pump doesn't hum like it's supposed to, it's dead silent...

So I guess it's time for a new pump. The truck has 208K on it, and I'm not the original owner... so this could be (probably is) the original pump.

My question is, which pump would be best to replace it with? I'm hearing that Bosch makes the best components in fuel systems, and that the Bosch would be a better choice than the GM OEM Delphi pump. I have read that I should avoid Carter fuel pumps, as well as Airtex.

I guess my friend and I will do the job at his garage, where he has a lift so we can drop the tank. Others say that it's easier to remove the truck bed and do it that way...

I plan on replacing the mesh fuel strainer, as well as the fuel filter, and will clean out the tank as best I can.

Is there any further advice any of you can give so I don't mess this job up?


I'll state the obvious here although it sounds like you have it all covered....

Did you check the fuel pump relay too?

It helps a ton to take another little electric pump and get all that fuel out of the tank before you drop it!
I have seen it done both ways and removing the truck box is the way to go IMO. As for the fuel pumps, the only brand I have used is Carter. We have had good luck with them and they are made in the USA.
I replaced the fuel pump in my 93 Suburban. Of course here I had to drop the tank.

When you drop the tank, you first drop it 3-4 inches, then undo wiring and lines then drop it the rest of the way.

When I first replaced the fuel pump, I snapped the rusty fuel lines that are part of the fuel sender assembly. No real way to prevent that except to maybe spray on PB Blaster for a day or two.

I used toilet seal wax to cover back up the area where the sender assembly goes.
That toilet seat wax would have been a great idea for me... I did pack it well with grease, in hopes of keeping out moisture in that area.

But I have replaced the pump already, today, and the truck is back running.

I did verify that the fuel pump relay was good prior to dropping the tank.

A friend and I were able to drop the tank, and drive to Advance Auto (5 minutes away) and pick up a Bosch pump and a new strainer... and get back and install it and put the tank back on in under 2 hours.

We work fast, but that's the honest truth. Things went quite well, as I believe that God blessed our efforts today.

Thanks for the advice. I hope everyone's pump replacement will go as well as mine did.

I think we went through about a gallon and half of iced tea today. :)

For the archives... here is a rundown on what we did:

We raised the back end of the truck up about 6 inches. Depending on your truck's height, you might be able to skip this step.

We siphoned as much fuel from the tank as possible. I think I left 3 or 4 gallons in there.

We removed the screws that hold the filler neck in place, accessed from inside the tank fill door.

We removed the bolts securing the looms which hold the fuel lines and brake lines in place along the frame rail. There were 4 on my truck, but it's long... :)

We placed a large block under the tank, so that it would not drop too far and damage the lines. I used a block of fire wood, but you could use milk crates and slabs of wood, or whatever...

We then removed the two tank strap bolts. Oil these from above if at all possible, for ease of removal. They're pretty long, too. :)

We then dropped the tank down onto the block, which allowed access to unhook the lines on top of the tank.

We removed the bolts for two ground straps, one to the filler neck area, and another to the frame rail. These wires were part of the wiring harness for the fuel tank. Unplug the wiring harness, of course...

We removed the two fuel lines (pressure and return) on the tank. On my 1996 model truck, these were not the compression fittings, but rather bolt coupled fittings, which required a 3/4 inch wrench and a 5/8 inch wrench. I was sure to mark which line was which, using colored zip ties.

We disconnected other vent lines, etc., which was pretty easy, and lowered the tank to the ground, bringing the filler neck and hose across the frame rail.

Then we used a hammer and blunt screwdriver to tap the locking tabs for the fuel pump retainer ring out of lock position, then we tapped the fuel pump retainer ring in a counter-clockwise direction (yours might go differently, so be sure to watch what you're doing)... then the pump was lifted out.

The new pump installs per directions which you should find in the box. I researched the reliability factor of various pumps on the market and a near consensus said that the Bosch turbine pump--which eliminates the pulsator which other pumps use--was the most reliable. The Bosch pump does not make that whining noise we all have come to love, but I am given to understand that it doesn't labor as much as other pumps to accomplish the same pressures. Take that for what it's worth. I'm sure there are other good pumps out there. The OEM Delphi in my truck lasted over 200K miles (it did not appear this tank had ever been dropped, or the pump removed... I got the truck used). Another note for those who may use the Bosch turbine pump (about 100 dollars at Advance Auto--and it has a lifetime warranty also, which is bold on Bosch's part, showing ultimate confidence in their product)... but what I was going to say is that you will use a small rubber connecting hose, which is included with the Bosch pump number 69225, to replace the pulsator unit. That pulsator just pulls right off the fuel lines.

I used some heavy grease to pack into the crevice when we installed the new pump. Someone else mentioned that toilet seat wax is good for keeping dirt and moisture from creeping in around the pump port in the tank. I wish I'd known to use that before I did the job, because it sounded like a good idea.

Anyway, installation of the tank is of course in reverse order. If all goes well, your truck will run once again... :)

The best fuel pump for GMs is Delphi!Delphi pumps last longer than Carter pumps,put in 2 of them in an Oldsmobile and they failed.Did a third time and put in a Delphi pump which has not come back yet.You can get a Delphi pump from your nearest Carquest parts store,any place that sells AC Delco parts or the dealer.Aftermarket fuel pumps are 100% piece of junk and wil not warranty any defective pumps calling it this: installer error.Airtex is know for this and are the worst pumps out there,put 6 of them in one Chevy truck.A plugged up fuel filter will take out a fuel pump
Quite possibly so... (that the Delphi is best).

As mentioned, my truck still had its original at 208K, so it did a good job that long.

I did read that Carters were not as good as some others, and also read the cautions about Airtex pumps as well.

I read nothing but good about the Bosch, and with the lifetime warranty it had I decided to give it a shot.

If it fails early, I'll definitely put a Delphi back in there...

I have come to trust Bosch over the years, as I've never been let down by any of their stuff (batteries, spark plugs, etc.,)... so here is hoping this pump will be no exception. :)

Someone else mentioned that toilet seat wax is good for keeping dirt and moisture from creeping in around the pump port in the tank. I wish I'd known to use that before I did the job, because it sounded like a good idea.

That's not the primary reason for the sealing, Dan. It's so that your EVAP:pURGE cycle won't throw a code.

My buddy's son had this happen (either 96 or 97 1/2 ton). Apparently a few had issues with the vapor system and the dealer fix was to melt some type of wax into the locking ring. In his case, it melted some of the wires, but didn't show up for many years. He kept blowing ECM fuses until he pulled the FP relay. Figured it was the pump ..replaced it ..same deal a few days later. Finally tracked it down to the wires.
Thanks Gary. That's good info. My tank seemed to have some sort of waxy seal around the pump port. I'll remember this in case it starts throwing codes.

Not open for further replies.