Trebor66

Has anybody had the problem of the gas gage not reading correctly?
Replaced sending unit and pump 2 years ago.Already checked sender and grounds and plug behind instrument cluster.With no change.

wrench97

Does it read the same all the time or hang at 1/2 or only go to 1/4 reading?

Trebor66

When the key is first turned on it may read the correct amount,but then move to 1/2 and maybe move on over to full then back.
This may not be related .I have seen my temp gage "twitch" a little never going over the actual temp.It would stop with a thump of the gage.

mack1

Hi Trebor66 and welcome to TSF,

Below is attached a print of the gauge circuit on a 96 S10. Might be the same as your 2000 or maybe not. Normally these prints are not shown in Haynes or Chilton manuals. This one is from Alldata. The red mark includes the circuit from "Hot In Run Or Start" source of power for the gauge. The blue includes the circuit that goes from the instrument, through the float sensor, and to ground at G106 (black wire with white stripe). The green circles a wire to ground that is probably used to make the gage move from bottom to zero fuel if the float valve is disconnected (not sure about that, just a guess) Except for the power source (red circle), I see no relation between the fuel gauge and the temp sensor.

You might check the ground at g106 back at the gas tank. You could measure the 12 volts the fuse block. Should be a good solid 12 volts when the ignition switch is turned on.

Hope this helps,
Mack1

mack1

and as usual, I forgot to send the print.
fuel gauge.jpg

Trebor66

THANK YOU SO MUCH !!!!!!!!!!!!!!!!!!!!! This will help.Mack1 I will make another posting after I check a few things.

Tyree

Digital or Analog gauge cluster?

Trebor66

Analog
Just so you know I have worked on industrial plastic machinery for 25+ years,and have checked all the possible causes.This gauge problem is a hair puller.

Trebor66

Ok guys the problem child is the sending unit its self.That they don't sell without the pump.Is there any way to repair that unit.The problem area is only from hafe a tank and below.Its only 2 years old and a new one is $230.00

wrench97

It's usually a wire wrapped around a plastic insulator with a contact that runs up and down the winding to increase or decrease resistance to ground, sometimes the wire breaks sometimes the contact loses contact. I haven't spent a lot of time trying but never had much success if the wire is broken.

Trebor66

Well let me tell you this 97.
I removed the bed of my truck took out the pump sender unit,and moved the float through its rage of motion,while watching the gauge.It moved just like it should,reinstalled unit and 3days later same thing.ONLY when it gets below hafe a tank does it start reading wrong.As gas goes down it starts to go up till its to the far right past full.

mack1

Check the ground connection between the float sensor and ground. Wire 451 black with white stripe.

Trebor66

let me know if yall think this is possible.
Could the hole in the plastic ,that is the pivot point for the float be worn to the point it is not contacting the slide of the sending unit.

mack1

If you have it out of the tank, hook your ohm meter to the wiper lead and see if you can duplicate the problem by lifting, wiggling, pushing each dirrection, etc. actions on the float. If it is solid as a rock doing that, the problem will have to be elsewhere.