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Fuel Pump Noises

kc5deb

By kc5deb
in Ask A GM Technician

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kc5deb Enthusiast

kc5deb

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My truck is a 2002 GMC Sierra 2500 4x4 with the 6.0L. Currently it's got 140,000 miles (give or take a few)

 

A few days ago, I was driving down the highway when suddenly all power just went out of the truck. I was able to pull over to the side of the road; it never died or ran rough like it was missing, but, when I pulled over, it was idling a little lower than normal. I don't know if it makes much of a difference, but, I also noticed that the A/C just wasn't cooling. It was set as cold as it could get, and it was just "comfortable"; normally, even on a day as hot as it was, it would freeze me out.

 

There were no codes or warnings, temp on the engine and transmission were normal. I turned off the engine, let it sit for a few minutes, and started it again. I pulled back on the highway and it seemed to have most of it's power back as I drove it around most the rest of the afternoon (and the A/C went back to freezing me out like it normally does).

 

I talked to a few mechanic friends of mine I trust, and they suggested the fuel filter... ESPECIALLY after I told them I had never replaced it, and they told me it needed to be replaced at LEAST every 15,000-20,000 (if not more often).

 

I replaced the fuel filter this afternoon, and sure enough, it was plugged so bad that I thought I was going to blow a lung trying to blow air through it. It dawned on me too that the high pitched "large angry mosquito" noise it usually makes is now gone... honestly, I don't remember hearing it the last month or so like I have been the last year or so. I was concerned about this noise before, and a few mechanics told me that the fuel pumps just "whine" sometimes, and to not worry about it.

 

I am noticing now (and I noticed that it was doing it after the other day's "episode" too) that the truck seems to be surging just a bit. Nothing that's going to throw you in and out of the seat, but, it's a bit noticeable.

 

I also put my ear against the gas tank while the engine was running, and I can hear some odd noises....

 

One of which is a slight clunking/clattering noise; the kind you hear from a cheap fan from walmart when a bearing is going out in it's motor.

 

The other is a whining noise that goes up and down in speed, like a motor trying to spin up, then spin down, and it does it in nonsensical way with no repetitive pattern to it.

 

Everyone's opinion is that the fuel pump is going out (and probably soon), and with the way I treated it by not replacing my fuel filter like I should have, and the fact that it's never been replaced in it's 140,000 mile life, I tend to agree. But, I'm the kind of person who would like a few more opinions before I dump $600+ in replacing the fuel pump. Not that I don't trust my friends... I just don't like spending money... especially money on replacing something that it still working good enough to keep my truck running for the moment.

 

Opinions? Easy way to tell if it's the fuel pump or not? Are the noises I hear indicative of a faulty fuel pump?

txab Senior Enthusiast

txab

Posted
Posted
Opinions? Easy way to tell if it's the fuel pump or not? Are the noises I hear indicative of a faulty fuel pump?

I'd say so. You could take pressure readings to see if it is in spec.

 

You could drive till it dies completely. But it probably has seen it's better days. 140k under the conditions you put it through it has done pretty well.

ColoradoSkiCountry Senior Enthusiast

ColoradoSkiCountry

Posted
Posted

If the pump has been having to work hard to push fuel thru a clogged filter even for a short period of time, you can pretty much count on needing to replace the pump soon. You may also consider replacing the fuel pressure regulator while your at it. They are known to not be very reliable on the GMT-800s.

minibike132 Senior Enthusiast

minibike132

Posted
Posted
I am noticing now (and I noticed that it was doing it after the other day's "episode" too) that the truck seems to be surging just a bit. Nothing that's going to throw you in and out of the seat, but, it's a bit noticeable.

 

 

You are probably looking at a pump pretty soon noises or no noises just based on miles and severe abuse (shame shame on you).

 

The surging you notice could also be becasue of the filter replacement, for two reasons. The long term fuel trims learned are going to be very lean, you surprised the truck by giving it lots more fuel then it is used to. Second the trans shift adapts get exaggerated with low fuel delivery the same as the fuel trims. Changing the fuel volume will cause the trans to flare a little feeling like a surge.

 

If i replaced a filter that had tons of miles on it I would reset the fuel trims and the shift adapts. I know it's not as easy as clearing codes with a scan tool and I'm pretty sure the trims and adapts will not reset with a battery disconnect either. The only way I know of clearing them is to use a scan tool's special functions to reset them. The factory tool (tech-2) is the one I use. Others like Snap-On's Solus are able to do it but no one that isn't at a well equipt shop will have a scanner with the ability to do it.

 

Unless the pump just dies on you, you probably are not going to know what is going on without spending a few bucks for the resets and/or fuel pressure and volume tests.

  • 2 weeks later...
kc5deb Enthusiast

kc5deb

Posted
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Posted

Update:

 

Took my truck in to the dealer, and my trusty mechanic hooked up the pressure gauge. It was dipping down to 35, where the mechanic said it should be at least around 50.

 

Dealer replaced the fuel pump, and while it runs better (tows a trailer MUCH better), it still has a slight bit of a surge, and still doesn't quite feel like it's got the power it used to.

 

Time to take it back and have them reset the fuel trims and run a batch of injector cleaner?

 

BTW, I still have suspicions that I got a bad tank of gas. I fill up at one of the only 2 stations in town that carries 93 octane fuel, and I'm quite sure that I'm one of the few that fills up at that station who buys 93... It was also after a good amount of rain. Local towns around have had problems in the past where after a good rain, water gets into the station's fuel tanks, although I haven't heard of any station around here having that issue.

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