Fuel gauge issue, I'm stumped

[phishfud]

The fuel gauge on my 84 hasn't worked right since I got the truck. Fill the tank, and you might see the gauge read half. I found a reciept for a new sending unit that the PO put in a little over a year ago. When I dropped the tank, it looked new, so I reinstalled it. I swapped out a different fuel gauge as well with no change. If I connect my ohm meter to the pin on the sending unit and then to ground, I get about 45 ohms. If I test the clips in the dash, I get like 24 ohms. I figured it was wiring somewhere, so I ran all new wires to bypass the factory stuff, just as a test. No change at all. Gauge reads less than a quarter tank. If I pull the sending wire from the unit, gauge pegs full, which I thought was normal. Do I have a bad sending unit after all? Any help would be great. Thanks.

Terry

[boxrodz]

Terry -
If you can pull the sending unit, test the resistance of the unit while moving the float lever up and down. It should register a reading between 0 and 90 ohms. If you get no reading or a constant reading (like 45 ohms) then the unit may be bad. The 45 ohm reading does explain why your fuel gauge only registers half. I'm not certain why you measure 24 ohms at the dash. You should see the same resistance at the dash connectors as you do at the sending unit. If you measured the resistance with the connector connected to the dash cluster, you may also be reading the shunt(?) resistance of the fuel gauge. That could explain your 24 ohm reading. Check out this link http://67-72chevytrucks.com/vboard/s...d.php?t=179942 for further explanation on how to check the fuel gauge. Good luck.