'99 NBS fuel pump

[53burb]

I have a '99 NBS 1/2ton 4x4 with a 4.3/5 spd manual tranny. Anyways, the fuel pump was replaced a couple of years ago, NOT by me. It was fine at first, then noticed the pump humming shortly afterwards. I finally pulled the bed off about 6 months ago to look at it. The lock ring wasn't on correctly & the pump was loose. Put the lock ring on correctly, problem was fixed...so I thought. It's now making the same noise again. I haven't pulled the bed off yet, but I'm sure of the problem. Anyone ever hear of this?? One guy my wife spoke to about this said it was common in GM trucks, but I "googled" it & didn't see anything. I know I put the ring on correctly & was real tight & locked in, but.....Any ideas?? The truck isn't used as 4x4, so no off-roading....

[Tater]

I have a 98 Silverado that does the same thing.It's been doing it since I bought it in 2000.

[53burb]

really?? how long does it go before it happens again once you fix it?? The only thing I can think of off hand, is to use some gasket material or ??? to make it tighter when I lock the ring down.

[Tater]

I've never changed the fuel pump.It hums for about 30 seconds everytime I shut it off.

[bwood]

The humming is normal as this is the sound of the pump priming, it also hums while the truck is running, you just can't hear it over the engine. The noise that 53burb is speaking of is apperantly due to a loose pump retaining ring. When you lock the ring, how do you do it? I believe you are suppost to use a block of wood or a BRASS drift and tap it down. I have never heard of one coming loose on its own. I did the pump in mine about 4 years ago and all is still good. Is is possible that althought the pump works, it is the wrong pump? The pump should have a 3 digit code on it (TCU or TCF), call a parts house and see it they give options for different fuel pumps according to that code. Also to the tabs on tank look damaged? I believe there is an oring associated with the seal at the top of the pump, is it there, or damaged? As for you idea to use some gasket material (I assume you mean RTV or something similar), Just make sure it is fuel safe.

[53burb]

I locked the ring by putting it on then hitting the ring with a hammer & screwdriver until it is locked in. I remember making sure the tab was fully "out" & not depressed when I was done to make sure it was locked in. It fit tight like it should. The ring felt real tight & the pump seemed to fit ok. I will have to check the P/N. It is a Delphi unit that I got from NAPA. I believe the seal was there. I'm pretty sure that it was. I did the pump in my '04 Burb a week before this one & I R & R the pump the same way.

[53burb]

I finally removed the bed from the truck yesterday & the pump was on fine. I guess it's just a little noisier that I expected. It's proably out of warranty now anyways.

[Gray Ghost]

Yep...our S10 sang like a bird for a couple of years before it went out. Nothing was loose on ours.

[BACKYARD88]

Sometimes they go years making noise, and somen are much louder than others. GM actually stopped us from replacing them under warranty for noise back in the late 90s.