I’ve been driving around depending on my odometer to tell me when I should fill up my fuel tank. It’s left me high and dry a couple of times, and I have been attempting to get to the bottom of the broken fuel gauge issue. I tried to fix the sending unit ground, but it didn’t work. The gauge is pegged all the way to the right, so is it a bad sending unit, ground, or something else?:confused:

i dont think it is a ground issue. but i am assuming it is a stock fuel gauge... if so if i am not mistaken if the ground is bad it will peg to the left "empty". Any frayed wires? voltage is correct? check with ohm meter to see if it is in range should be 0-90 ohms. check the ohms with the wire detached from the sending unit to a good ground, make sure your not touching the metal probes as it will read wrong. try and empty the tank as much as possible, the ohm reading should read near zero. full would be 90.
hope this helps
****as always be careful around gas tank. and such.******

hope that helped

Sorry about the delay, I was out in the field doing training (Marine Corps). I'll check the Ohms on the sending unit and ground this weekend (if the wife doesn't have plans for me). I'll let you know as soon as I figure it out. Thanks for the info, it should be a big help.

If it is pegged to the right, the wire from the guage to the sending unit is open. (it might be the ground, but usually isn't)

You can test the wire by grounding it. If the guage goes to empty, it is normal. The resistance of the sending unit, measured to ground, is about 100 ohms with a full tank, 5 ohms with empty tank.

this is a great ?. I am having the same problem with my 82 k10. I thought about changing the the selector valve where the harness is connected. seeing as my tanks aren't exactly the worlds best at switching back and forth. But my right tank is pegged to the right also and my left tank has a mind of its own. I'd like some help myself!!!

first off i would make sure that the ground on both tanks are good, dont assume the current location is good!! My best suggestion, would be to add ground to the frame. to the motor then the neg battery post. this will make sure that the frame has good ground. Then find a spot on the frame near both tanks, sand/grind it down to you see shiny metal (shouldnt take much), get a self tapping screw or drill and tap a hole for a loop/hoop connector splice the connector into the orginal ground and secure it tight. now test the gauges if not correct, then follow mine and/or dan's directions to test the gauge then once determined gauge and ground are good, then test the sending unit leads for ohms 0-90 (that is what mine registered mine is for 75 chevy K10) or dan's 5- 100 i think either way will get you in the right place. the most important part is to make sure ground is good!!
chris

I had the same problem, there is a resistor on the back of the gauge mine was broken. As I remenber it should be 90-100ohm. I tested with a 50 ohm resitor instead of the sender unit, if the gauge is ok it shows 1/2 full. I removed my tank just to find thatt the problem was in yhe other end.

I finally got a chance to work on the fuel guage issue. I droped the tank and discovered that the tank was from a salvage yard and that the ground wire was rusted and was just being held together by the wires being twisted together. I figured that was my issue, but I wasn't taking any chances. I took the sending unit out and found that it was also faulty. I attached my Ohm meter and found it read infinate. I put the new sending unit in, put the tank back in the truck, and I finally have an operational fuel guage! Thanks for the assistance.