As anyone run into a sticking fuel gauge? Last week I almost ran out of fuel. I had two bars left and the reserve just came on. The "check gauge" light did not appear. I filled up the car and the gauge went to full. My first bar dropped after about 90 miles of city driving. After about about 30 more miles it dropped to just over half. It seems like the float is getting stuck. Although the gauge always dropped faster after the 1/2 way mark, it seems to stay at a point longer and then drop a few bars, then stay again. As anyone run into this and is it possible to clean / lubricate the float pivot point?

Thanks for any thoughts.

Jim

 

..there is a simple fix for this assuming it is just a dirty sendig unit. check your pm's . i would post picts but, i always screw that up!

 

.......check Your E-mail...

 

Initially I had major problems when I first got my car with the variable resistor on the float unit. It was completely corroded, basically open. Spent hours carefully using emory cloth on the 2 wipers and the wire wound resistor to clean it up. Did this until the resistive reading was smooth and even when I moved the wiper. I got is about 98% of what I thought it should be. When I reconnected it back to the system, still out of the tank and moved the wiper (float) the digital fuel gauge worked fine. The small imperfections did not affect the digital read out or make it jumpy. There is a range of resistance that each bar will respond to. . Point is the reaction time was pretty quick from what I remember. I moved the float, the gauge responded. If you have some corrosion on the contacts or wiper it could cause your problem. The only way to really know is to take it out and manually measure it. Analog ohm meters work better for these kinds of jobs, digitals will work to but the update time of the meter is to long when the resistance jumps. The analog gives you an better picture, exact accuracy is not that important here.

Gas Gauge Indication Fix - 94 (and more)

Tired of not having the gas gauge drop as you use gas. The inaccuracy was to much for me to stand so I investigated the problem. According to specs the float unit has a range of 0 to 90 ohms. I measured 20 to 110 ohms on my float unit. The 20 ohms representing the empty end and the 110 representing the full side (most other cars the low represented full but in the digital world they can do what the want).

The basic problem is the resistance doesn't not drop fast enough as gas is removed from the tank. I had to move the float arm to the 65 ohm point before it would indicate a one bar drop on the gas gauge. 75 to 110 ohms read full. It was not before I got down to about 37 ohms that I got a half tank indication on gauge. In reality the float resistance range is not properly matched to the electronics in the CCM. How to fix properly, you can’t unless you rewind the float wires (I don’t think so). So the best you can do (rather than redesign CCM) is to compensate for the problem. Make the resistance read lower faster as gas is burned. I added a 180 ohm resistor (yours might me slightly different) across the float unit, this will accomplish this. To little resistance and you will not get a full reading, to much and you are giving away accuracy which you a targeting in on. If I really really fill my tank I can get a full indication, if I let it click once or twice I might get a one bar down. I’m on the edge and I can live with that. But I do get more accurate readings right down to ¼ tank. Its not perfect, but I’m within 2 gallons or less when I get gas.

All you need to do is to add the resistor across the tank wiring. You do not need to take out the tank unit. Just remove the gas door and the rubber boot. Come back 6 inches or so from the tank unit and skin back the black and purple wires. I did not cut the wires, just removed about ¼ inch of insulation, wound the resistor ends around each wire and tape it
up. I don’t think I soldered mine because I was not sure of the resistor I wanted to use and how the whole thing was going to work out so wanted the option of removing it easy. So temporary became permanent 2 years ago. Hope this can be of use to some of you.

P.S. - There are 3 wires. Black is ground and gray is power for the pump. The purple wire was not indicated the color for the float in the GM book, think it was green, don’t know why, will check again.