2005 Chevy Trailblazer fuel light?

Most likely a bad fuel level sensor in the tank. There is a possibility that it could be a loose wiring connector somewhere in the harness, but that is rare.

Sounds like something is wrong with the sending unit. But before you take it in, try filling up with BP gas. I had to change the unit and fuel pump on my Caprice and it still didn't work right after that. And that was with a Delco part. I would fill up and the needle wouldn't move or it would bounce up and down then go to empty. I started using BP fuel and it started working right. Try a tank full, it might save you hundreds of dollars.

it's more than likely the fuel sending unit located inside the gas tank, be sure when you take it to be replaced that the tank is almost empty, it will make the job a whole lot easier and the mechanic will appreciate it. they are pretty expensive but be sure and get a new one and not a used one, only other thing you can do is set the trip odometer to 0 and note how many miles are on it when it runs out of gas, then you would know when your getting low on fuel.

From what you said, most likely, it's the fuel pump. Don't replace any part unless it's broken or wornout. You can test the fuel pump's flow & psi at the fuel rail.Shops charge to empty & remove the gas to replace the pump.BUT There's a really cool short cut that even the dealerships do. Cut a 3 sided, 6"x6" flap in the floor & peel the sheetmetal back.Change the pump, push the floor back & seal it. =^ )

Your fuel sending unit is haywire. Only fix is to replace the fuel pump sending unit assembly.Its in the gas tank and will have to remove tank to do so................Common problem on GM ...............md

That is true i had that happen in my tahoe it cost me 300$ but i did it my self in a shop it will be about 400-500$ good luck.