Fuel Gauge reads always full?

[Eckhart]

Hello everyone!

I was recently gifted a 2002 Tahoe with 132k on the clock, passed emissions and safety great and had no issues until this morning. Yesterday my fuel gauge was reading just under 3/4 tank; when I started it up this morning it jumped to over the F line and stayed there for the rest of the day, about 30 minutes total of driving. Took a second trip out today and it also read Full. Seems like it's suddenly stuck reading full.

Most fuel gauge issues I've noted on the forum here have been an erratically-moving gauge caused by a bad sending unit, or a gauge that never goes over empty due to the same, or gauges that only read in quarter-tank increments also caused by a poor sending unit.

I can't afford to have a sending unit replaced at a mechanic shop and, living in an apartment building, can't do it myself. Do y'all think there's any chance of it being something easy fixable, like a stuck float? Think I should run some fuel system cleaner through it and beat on the tank a bit? Any thoughts?

Thanks!

 

[clkelley]

Welcome to the neighborhood!

I don't think it is the sending unit. I am thinking that it may be the stepper motor behind that gauge in the cluster. They are cheaper and easier to repair than the fuel level sending unit.

 

[Eckhart]

Sounds possible, though slightly odd, perhaps I misrepresented the problem; the gauge does read under E with the ignition in Off, but jumps straight to Full when given power. Could the stepper motor issue cause that?

 

[clkelley]

Yes Sir, it could and I have seen it a number of times. I have seen them have a steady bounce from bottom to the top, be pegged at the top and stuck on 1/4 tank, but usually they hit zero and look normal when the key is off.

 

[Eckhart]

I'll bet that's it then; I just remember that, earlier today, when I got back into the truck at one of my stops the fuel gauge was reading at a quarter tank with the power off. Normally it had always returned to E when not getting power and a bad sending unit wouldn't cause that, right?

Looks like I can replace it on my own for only $10 in parts and a bit of soldering time. Looks like I got a new weekend project! Might as well install an AUX jack while I'm at it.

 

[clkelley]

Yeah, if it was sitting at 1/4 tank with the key off I am almost 100% that the stepper motor is your issue.

Maybe take a few pics when you do it and start a DIY here on the forum? Either way, good luck getting here worked out.

 

[Eckhart]

Sounds good! I can do a DIY for the AUX and stepper motor at the same time if I get around to it. I'm going top off the tank tomorrow and throw in some Techron, reset the trip odometer, and run it for 100-200 miles and if still keeps going from E to F with the occasional power-off stop at a quarter tank I'll order up a stepper motor and solder it on up and do that DIY.

 

[arz71]

Sounds good! I can do a DIY for the AUX and stepper motor at the same time if I get around to it. I'm going top off the tank tomorrow and throw in some Techron, reset the trip odometer, and run it for 100-200 miles and if still keeps going from E to F with the occasional power-off stop at a quarter tank I'll order up a stepper motor and solder it on up and do that DIY.

I have a 2000 Chevrolet Silverado Z71 and when you turn the key off (goes to empty) start it up and it goes to full (and stays there).

Is this the stepper motor you were referring to and how did you fix yours?

Any help advice would be great.

 

[Eckhart]

I have a 2000 Chevrolet Silverado Z71 and when you turn the key off (goes to empty) start it up and it goes to full (and stays there).

Is this the stepper motor you were referring to and how did you fix yours?

Any help advice would be great.

My issue turned out to be with the fuel level sending unit in the tank. Before I got around to taking the gauges apart I went out and bought some Techron and added it to the tank, then beat on the outside a bit. The next day, the fuel gauge was working as intended - perhaps a stuck float or something of the kind.

That said, I'm using the trip odometer as a back-up still, since these trucks should get around 200mi to a tank on a bad day. I have noticed that the gauge will sit at F for the first 75 miles on a tank, then start going down from there; a half-tank seems to occur at what is, by volume, a quarter of the fuel remaining.

 

[arz71]

What version of techron did you get and where did you tap on the tank at side or bottom?

I would be very hesitant to mess with the guages, it was working just fine until I filled up the tank. Then it was stuck.

 

[Eckhart]

What version of techron did you get and where did you tap on the tank at side or bottom?

I would be very hesitant to mess with the guages, it was working just fine until I filled up the tank. Then it was stuck.

Just normal Techron from autozone, like this;
http://www.amazon.com/Chevron-67740...e=UTF8&qid=1368663084&sr=8-2&keywords=techron

And I just beat a bit on every side of the tank, and the bottom. Couldn't reach the top for obvious reasons, and just used the heel of my hand. I figure I either knocked something loose, the techron fixed it, or it just happened to fix itself.

 

[arz71]

Just normal Techron from autozone, like this;
http://www.amazon.com/Chevron-67740...e=UTF8&qid=1368663084&sr=8-2&keywords=techron

And I just beat a bit on every side of the tank, and the bottom. Couldn't reach the top for obvious reasons, and just used the heel of my hand. I figure I either knocked something loose, the techron fixed it, or it just happened to fix itself.

Thank you, I am sure mine is since I filled it up and then it was 'stuck'.

The best truck(s) to own is one you have the title's to!

 

[Bwalker70]

It's been awhile, but looking.

I know this thread is old but I just found it, and hope it can help me out.

we have a 2002 Tahoe, and when the tank is full, the gauge will read empty for a while, then flip to full. After a short while it will go back down to E, and stay there for some time. You think this is the sensor problem or what else could it be. Thanks in advance for the help. Have a great day and God bless.

 

[Eckhart]

Most likely a fuel level sensor problem. I'm still experiencing weird fuel gauge readings, especially after filling up; the needle will go back and forth between full and empty with the accompanying "Low Fuel" warning on the display.

I've resorted to just using my trip odometer to gauge my fuel, since I don't trust my gauge. I know I can get at least 200 miles on a tank, 300 on the highway, so I just top off when the trip goes past 200 or nears 300 on road trips.

To replace the sensor you have to drop the tank and, to my knowledge, it's part of the fuel pump assembly. I figured it wasn't worth the effort to fix and plan to just wait until the fuel pump or tank needs servicing.

 

[h82work1]

Guys i'm mechanical inclined and did the stepper motor thing and it is not just a motor replacement thing you have to take the top part of the old one off diode I think it called and you have to solder the old one on the new one also what if the old one is bad I did this and still had same problem I have yet to fix it or find the problem mine was erratic I got ones from junk with same problems I would like to send it off to a place that could check it and tell me if it is the gauge any suggestions