my gas gauge fluctuates when it reaches about 1/4 tank or so.... only when car is on. As I drive will show 1/4 tank, then it moves up to 1/2 tank or 3/4, when i shut car off it returns to the normal position. When the tank is full or half at least, it always stays put..... could this just be a sensor issue? easy fix? It's a 99 Z34

 

I think this is normal. GM tanks tend to be top heavy so it will move around a little more when its below 1/2.

 

I started having the same characteristics. I'm assuming a fuel sender replacement in the near future

 

You need a new sending until. If I was you, i'd repalce the whole fuel pump and sending unit all at the sametime.

 

Yup that was the first stage of my sending unit problem. At first it does that. then it will read a half tank then it goes to straight full all the time and doesn't work at all. Which is where mine is at. Been to lazy to replace it so I just do the mileage calculation. When I get back and I do my top swap build I'll pull it out. But you should start looking into it now. Everyone else in this thread is absolutely correct.

 

Everyones correct, (fuel sender unit) had this same exact issue but replaced under warranty, luckily.

Good luck man.

 

I had the same issue and all I did was bend the small metal contact resistor arms a little bit. It wasn't quite touching the resistor so I wasn't getting a good reading. Problem solved

 

bending the arms a bit do you have to pull the whole pump and drop the tank or can you go through the trunk???

 

our 03 Cavalier LS SPORT does the same thing but its not enuf to bother me

 

There is an access panel located in the trunk. A few screws and viola you're pump is in your hands.