Fuel gauge problem

[FlameOut]

I know this item has been addressed a million times, And I've read many of the threads, but is there a way to test the actual gauge with the instrument cluster out of the truck?

I pulled my seat and then removed the sending unit, thinking that was my problem, but I'm getting the 0-90 ohms when I test it, and when I manually operate the float when connected and grounded, I cant get past about 1/3 of a tank on the gauge.

I removed the instrument cluster, cleaned every connection, but still won't go past 1/3. I'm thinking the actual gauge might be bad, but not sure how to test it. I have the basic inst cluster with idiot lights, but also have a spare cluster with all gauges. Is there a way to test using the 2nd cluster that I have? Can the fuel gauge be removed from one and put into the other?

Everything appears to be properly grounded properly

[davepl]

Yes. A 12V signal through a 90 ohm resistor should read Full, and without the resistor should read Over Full when grounded. When no resistance (0 ohms) it should read empty.

I didn't have a 90 ohm resistor so I used 100, it was close. I would imagine a 45 or 50ohm should read half a tank?

For more info on bench-testing them:

http://www.modsandrods.tv/2012/03/29...uel-gas-gauge/

[FlameOut]

Thanks Dave. I checked an old stock of resistors that I had, but none close to 100 ohm. I may order a 100 ohm potentiometer, as suggested in your link. In the meantime, I removed the gas gauge from my spare cluster, but the two gas gauge nuts on rear of mmy original cluster won't budge. They just twist the pc board when I try to losen them

[VetteVet]

Here's a good link by our gauge testing expert.

[VetteVet]

Here's a link to our gauge testing expert. Tom T-Bone.

http://67-72chevytrucks.com/vboard/s...d.php?t=640615

[cdowns]

take a piece of wire and run a temp ground from the sending unit to the body of the truck

[FlameOut]

Thanks for the info, and that link, Tom. Very informative. I put about 5 gals of gas into my tank, removed the tan wire from the fuse panel and checked with my ohm meter. I got a reading of 34.6 ohm, so about 1/3 of a tank. Re installed the instrument cluster but needle barely moved. Showing a little under 1/4. I also noticed that when I turned on the headlight, I had no lights on the right half of my inst cluster, even though I know all bulbs are good. I think maybe the circuit board could be causing my problems