GMT 800 Fuel Pump - Preventive maintenance?

[Martinjmpr]

A couple of folks here have said that the fuel pump on the GMT800 trucks can be problematic. I haven't heard of this before, what are the symptoms? When (mileage wise) does this seem to occur, and is there any fix other than a pre-emptive replacement?
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I just want to make sure my Suburban continues to last as a tow vehicle and I'd hate to get broken down in the middle of BFE because of bad fuel pump.

 

[1stDeuce]

Generally, I figure when the pump starts getting loud, it's probably not a bad plan to replace it. Or if you test fuel pressure and find it lower than it's supposed to be.

I've got a 150k mile pump in my '02 GMC that is occasionally loud (a little marvel mystery oil tends to quiet it down for a few weeks) but the fuel pressure seems OK, so I still haven't changed it... They're so dang expensive!!!

If the pump does go out, the usual problem is that it fails to run after you shut the truck off and try to re-start it. The truck will start, run for a few seconds, and die as fuel rail pressure drops. Then it'll just crank, and you won't hear the pump run when you first key on. If that happens, you can almost always get the pump to run again by having someone crank on the engine (to energize the pump) while you bang on the bottom of the tank. (Hit it with a tire iron, chunk of 2x4, heavy boot, etc.) Hitting the tank must rattle the brushes in a worn out pump motor, and the pump will take off again.

After banging on the tank to get it going, it may be fine for a good while after, or it may not work again the next time you shut the truck off... Having to thump on the tank is a definite sign that you need to change the pump.

 

[PGW]

I have a Yukon XL 2500 (with two tanks) with about ~145k on it. Last year I replaced both fuel pumps as preventative maintenance and kept the old ones as spares. I also made access panels and cut out holes in the floor so I can R&R the pumps without dropping the tanks. The new pumps will probably last the remaining life of the vehicle but if it ever goes out on me cross country I will have a spare and can replace it fairly quickly. Also have the benefit of being able to periodically inspect and clean the pumps.

 

[Martinjmpr]

I have a Yukon XL 2500 (with two tanks) with about ~145k on it. Last year I replaced both fuel pumps as preventative maintenance and kept the old ones as spares. I also made access panels and cut out holes in the floor so I can R&R the pumps without dropping the tanks. The new pumps will probably last the remaining life of the vehicle but if it ever goes out on me cross country I will have a spare and can replace it fairly quickly. Also have the benefit of being able to periodically inspect and clean the pumps.

I thought the pump was inside the tank?

 

[Martinjmpr]

Generally, I figure when the pump starts getting loud, it's probably not a bad plan to replace it. Or if you test fuel pressure and find it lower than it's supposed to be.

What does it sound like? Should I hear it when the key is in the "on" position but engine not running? And I think my Scangauge can show fuel pressure, what should it be?

 

[Burb One]

On my 03 (6.0) I replaced two of them. The first (stock) lasted 100k, and a valve broke or wore out in it, where it wouldn't hold pressure from the last run, so it needed "two key turns" to prime and start the truck. I replaced it with an AirTec of which lasted a year and then stopped completely stopped after whining for a few months. Put in a Delco, and to my knowledge still works (sold the truck)

My 5.3 I currently have, I replaced the stock at 150k miles after it started whining with a AC delco. It's fine now at 214k, but I plan on replacing it soon, and carry the current one as a spare (Also want to cut a hole so I can access the pump without dropping the tank. )

They are definitely wear items, however I don't think they will strand you, they'll start whining before they go out. Make sure to get a quality replacement.

 

[4x4x4doors]

You might be able to hear the pump run with key in the on position and engine off normally but only after its been setting a while. Just because you hear it once an a while doesn't mean its gonna fail you.
By your own admission, you are a "belt AND suspenders" guy so your answer may be different but here's my take.
Some fail. Most don't. Internet wisdom (is that an oxymoron?) says keep the tank at least 1/4 filled always to ensure the pump is cooled/lubed. The failures (when they occur) are between 80K and 600K miles.
The pump is in the tank and drops in from the top. Hence why the hole cut in the floor may provide access. There have been cases where the suspected pump failure was actually a failure of the wire connections on top of the tank but its such a bear to R&R the tank that it all gets replaced anyway just to avoid doing THAT again.
If you ever have to kick it/beat it to get it working, you're on borrowed time.
Murphy says any failure that does occur will be right after you've put many gallons of heavy gasoline into the tank as the way to replace the pump is to drop the tank or lift the body completely off the frame.
If you do replace it, spend the extra money to buy an OEM pump. I can't recall ever hearing of an OEM replacement failing but I have heard of generic replacements lasting only 40K miles.
Some include the level mechanism as a part of the pump assembly, some don't.
In several hundred thousand miles of driving GM trucks, I've had to replace 2. One was because the tank had rusted so badly on top that the pump couldn't be salvaged when replacing the tank. The other was because level gauge had died and we couldn't clear an evap system code with an erratic level in the tank and I had to pass emissions inspection. (At that time, GM was only making the integrated ***'y available.)

 

[rayra]

Most of my reading of anecdotes has led me to believe the greatest problem lays with what I think of as 'mom taxis'. The pump is in the tank and cooled by the fuel. If the vehicle is typically or extensively driven with less than a quarter tank of gas - as in someone driving it around like that all the time and only throwing a few gallons of gas in at a time - it's gonna fail sooner rather than later.

That said, the missus' '05 Tahoe has 165k on it and going fine.

From what I've seen / read, you're more likely to get no notice of the pump quitting, rather than increased noise.

I've stated here a few times that I intend to deliberately change mine at a time of my choosing, rather than waiting for it to fail on me. And since much of driving is either commuting on L.A. freeways or in SoCal deserts, that heat also encourages me to do it sooner rather than later.

There are several interesting vids of people cutting holes in floor pans to get right at the top mounting ring of the pump. I had one in particular bookmarked but can't seem to find it right now. Guy laid out the grid and reference measurements, it was right under the 2nd row driver side seat. And he did a pretty decent job of patching it back shut again. I think it's a decent method. Beats my trying to wrestle it out from beneath, in my driveway. Be a good excuse for me to buy an air-powered nibbler, too. Spark-less cutting, clean and fast. Some work pop-riveting some sheet metal flanges around the opening edges overlapping from below, a fat sealing bead of 100% silicone caulk, drop the cut out piece in place, and over top it with either adhesive metal-foil tape (true 'duct' tape) or butyl rubber window flashing, or some of that sound-deadening rubber membrane. In and out in a jiffy with little mess or strain. That's worth cutting a hole in the floor. And part of why I sought / bought a 14yr-old vehicle. So I could modify it with little concern.

I'll see if I can find that vid I'm talking about.

eta found it with a few more key words

https://www.youtube.com/watch?v=Ho2pk8okztE


rockauto.com has the pumps for under $200.

 

[rayra]

'99 Suburban, in the rear

https://www.youtube.com/watch?v=chN4tRmBG5g

 

[PhilipE]

If you do replace it, spend the extra money to buy an OEM pump. I can't recall ever hearing of an OEM replacement failing but I have heard of generic replacements lasting only 40K miles.

The after market pumps have a life span just a little longer than the warranty. I went threw this on my son's 93 C10. The original pump died at 125K. He went threw a pump a year with after market pumps. Total of three after markets used. Then he bought an OEM replacement. That one lasted the rest of that trucks life. The truck had 275K on it when it died.

BTW the OEM pump cost $8. more than the after market replacements.

 

[digitaldelay]

Internet wisdom (is that an oxymoron?) says keep the tank at least 1/4 filled always to ensure the pump is cooled/lubed.

Murphy says any failure that does occur will be right after you've put many gallons of heavy gasoline into the tank

^^^All correct^^^

Jason

Sent from my SM-G920W8 using Tapatalk

 

[rayra]

BTW the OEM pump cost $8. more than the after market replacements.

maybe for his. My '02, rockauto has over a dozen vendors and the prices range from $88 to over $300. The lower appropriate Delco pump for mine is $172. Carter $158, Airtex $144
http://www.rockauto.com/en/catalog/...+1500,5.3l+v8,1380327,fuel/air,fuel+pump,6256

 

[ZMagic97]

I know this is old, but I believe Seafoam in the tank every oil change helps. Reason I say this:

My 05 Silverado used to misfire under load fairly often if held at higher RPMs. After trying to fix it myself, I took it to a local shop and they had it worked on for almost 2 weeks non stop. New injectors, fuel pressure regulator, distributor, cap, and rotor (it's a 4.3) on no real way to solve the issue. They did most of the parts and labor for free due to the length of time they had it and ever had a GM engineer that helped design the LS motors look at it. Without tearing the motor out and down, they thought a cam may be bouncing back and forth due to the distributor teeth being worn.

Truck ran better, but I felt like they missed something. Ran a bottle of seafoam the next tank and the issue was almost 100% gone. I suspect the truck may have been starving for fuel as it would fire normally again once the throttle was released.

Either way, my 05 Silverado with ~161,000mi and my 06 Sierra with ~138,000mi still have both stock fuel pumps.