2002 fuel gauge

AJ77

Well-known member
Joined
Oct 10, 2008
Messages
278
Location
Azle, Tx.
Anybody have a wiring diagram for a C5? I just bought an 02 and the fuel gauge just dropped to empty. I'm not sure where to start looking.
 
Anybody have a wiring diagram for a C5? I just bought an 02 and the fuel gauge just dropped to empty. I'm not sure where to start looking.

Did you try filling the tank???
























sorry, couldn't resist......:trumpet::trumpet::eek:
 
I guess I asked for that one! Yea, I've been through a tank and a half. It dropped to empty Sun. evening and then came back up about 30 min. later. Tues. It dropped again and hasn't come back. Tank is full. Read a thread on CAC talking about a Techron plus fuel additive that's supposed to remove deposits from the sending unit in the tank. They said it's a common problem with C5s. I'll see ig I can find some and try it. Not much money. Art
 
Found this info on the net:

Cause of erratic fuel gauge readings:
This condition may result when fuel blends containing aggressive sulphur compounds react with the fuel sender assembly, which may result in voltage spikes being induced on the fuel level signal to the PCM. Use of another fuel blend may reverse this reaction and return the system to normal operation.


I guess the "aggressive sulphur compounds" gum up the sensor? The Techron seems like it's worth a try.
 
Yea, I'm going to give it a shot. The car's under a 30 day warranty from Carmax, but I don't want to leave it with them if the Techron might fix it. I've still got three weeks to run a few tanks of fuel through it. In 1 week, I've put more miles on it than the original owner did in 6 months!
 
That's probably all the more reason to try it. If the car sat for long periods of time with the same gas in the tank, it's probably a good idea for the entire fuel system.
 
This is a common problem with the fuel gauges on the C5. Do what the bulletin says and see if it fixes it. It should read correct again after the fuel in the tank goes down some.
 
This is a common problem with the fuel gauges on the C5. Do what the bulletin says and see if it fixes it. It should read correct again after the fuel in the tank goes down some.

:eek::trumpet:

When the car stops, the tank IS empty, and the gauge is correcto mundo....

:banned:

Sorry I can't be more useful, only have vague recollections from other posts....

:banned:
 
That stuff is a magic potion!!!! Put 1 bottle in a full tank and didn't even drive 50 miles and the gauge started working again. I love it!
 
That stuff is a magic potion!!!! Put 1 bottle in a full tank and didn't even drive 50 miles and the gauge started working again. I love it!

I say this, I never had any gauge problems, but when battling some water/alky? in the fuel tank, I used a bunch of Techron to alleviate some of the run/idle problems.....but after time, it sorta lost effectiveness when I finally got smart and drained/cleaned the tank for the THIRD TIME in the 13 years I been here.....I found the problem for about 90% of the symptoms....but Techron does work.....

wooden be surprised that formula is nothing but Tetraethyl LEAD....

:banned::drink:
 
Well, I'm back. I've been through two tanks (with Techron +) and the gauge has stopped working twice since then. It just came back up yesterday. How much trouble is it to drop the tank in a C5? I know it's no big deal on a C3, I've had mine out a few times. Art
 
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