Erratic Fuel Gauge- bounces around between empty and 1/2

[NYC2004GXP]

Car has 101k. Two/three tanks ago when I used 16-17 gallons the fuel gauge would start bouncing around between an 1/8 -1/2 tank fuel reading. I tried a couple of bottles of gas tank/injector cleaner but the problem continues. Anybody got any ideas on cause and possible fixes?

Also, I have had this car for almost 4 years and have yet to see one other GXP in NYC

[CMNTMXR57]

2 common things.

1) In the tank, the fuel level sending unit and or the mechanism inside the tank.
2) Erratic stepper motor or instrument panel

If none of those are the problem, I'd start looking for a short in the harness.

[Gagger14]

Car has 101k. Two/three tanks ago when I used 16-17 gallons the fuel gauge would start bouncing around between an 1/8 -1/2 tank fuel reading. I tried a couple of bottles of gas tank/injector cleaner but the problem continues. Anybody got any ideas on cause and possible fixes?

Also, I have had this car for almost 4 years and have yet to see one other GXP in NYC

Not to completely change the topic, but I thought these cars were pretty rare... and then I saw 3 pearl white GXPs in MN in less than 24 hours. It was crazy.

As for your issue, if it is the fuel sending unit, its a pretty DIY repair. There is a tutorial on these forums and on YouTube that explain it extremely well.

If its the stepper motors in your instrument panels (which is most likely the issue I have), it will cost me about $190 to get all my stepper motors upgraded.

Just some FYIs. Good luck.

[sethjamesrimrodt]

You can do stepper motors yourself too as long as you can solder. We have three GXP's in a town of 30,000 people but we have a ton of 2000+ bonnevilles like 75 of them.

[CMNTMXR57]

There are a couple around me, including a white like yours (I forget the technical color name). Back when I had mine, her and I were next to one another at a light. Somehow mine finally got her attention and I waved and she looked at me like I had 8 heads. Even if you're not a "car" person, seeing a unique car, just like yours, you'd figure she might at least acknowledge it with a wave, maybe pull up her shirt, throw her undergarments in my passenger window, ask for a quickie, something... Nope!

[00Beast]

Even if you're not a "car" person, seeing a unique car, just like yours, you'd figure she might at least acknowledge it with a wave, maybe pull up her shirt, throw her undergarments in my passenger window, ask for a quickie, something... Nope!

New sig quote, LOL.

[CMNTMXR57]

I want royalties.

[nos4blood70]

http://www.youtube.com/watch?v=-7cY_IPCVfI

Here's part one for the fuel sender replacement.

Also, CMNTMXR57, you just made my day.. LMAO

[rwebb616]

You can do stepper motors yourself too as long as you can solder

I just did mine - 2005 GXP with 56,000 on it. I was having trouble with both the temp gauge and the fuel gauge but I replaced all of them. $22 for a set with free shipping on eBay.

I took a bunch of pictures and would be willing to post a write-up on how I did it if someone would wanna sticky it.

-Rich

[ericb]

In addition to the excellent info already supplied, switch your information center over to the "Miles-to-empty" setting. If it is also erratic, I would place more suspicion on the fuel tank sender than the stepper motors. If it remaiuns constant (and gauge fluctuates) then that could indicate the steppers.

The ECM gets it's info from the tank unit. If it sees it fluctuate, so will the miles to empty reading.

I've replaced my tank unit on my 2000 SSEi. That is exactly how it reacted.

[Bvill_GXP]

My GXP stared doing that and it was the "Erratic stepper motor or instrument panel" And it was replaced under warranty last year.... My G/F Grand prix is doing it now and it is the sending unit in the tank with the issue now.. But that's just a $25 fix..