jumpy gas guage

Hey all,
I have a 2000 GMC Sierra with 150,000 miles on it and the gas gauge is starting to get jumpy, says full when not and says empty when not and all the way in between. My research has turned up that the fuel sender is part of the fuel pump assembly so I cannot change one without the other. So if it is getting jumpy does that mean the fuel pump is on the way out or are they not related at all? I have never had the fuel pump changed before. I do not want to have this thing die when I need it most so I am hoping for some guidance. And is this a change I should leave to the pros? Thanks for all the help guys.

 

Usually an erratic gauge means a bad/loose connection somewhere. Electric fuel pumps tend to get noisy before they go out - usually enough warning so you don't get stranded.

 

It does sound like the sending unit.
As for one going will indicate the other is going... I wouldn't think so, but is still possible.

On your truck, I would assume it would be easier to change then it was on my buddy's Jimmy (pump failed on his).
For the Jimmy (in his driveway during the winter), right or wrong, we used a large tractor tube and a piece of plywood.
With the bolts broke loose, hoses disconnected and tank as empty as we could get it, we inflated the tub with the plywood on top until it was supporting the tank.
Removed the bolts and slowing let the air out of the tube to lower.
The tube slide well in the snow, so slid it out, did what needed to be done, and slid it back into place. Add air to the tube while the other person lines stuff up and reconnect. I'm pretty sure my buddy was partly lifting the tank when we added air. I was the one adding the air.

 

As stated bad connections can cause erratic readings as can a failing sending unit. You have been lucky to not have replaced the pump by now. Most people consider the best method to change fuel pumps on GM trucks is to remove the bed.

 

I would assume the under carrage of a truck in the OP area to be reaonably corrosion free and easier to drop, no?

Most of the GM cars I worked on (or owned) where easy to access from in the cabin as you remove the back seat, and find the access pannel.

 

Yes cars are a different story, but were talking trucks here.