Fuel gauge issue

[Sean Larabee]

Hello, I was wondering if someone could  please help me troubleshoot the issue with my fuel gauge in my 96 c/k1500 (454ss clone with 7.4l vortec). I replaced the fuel sending unit in the gas tank and that did nothing. Here is a video I posted on youtube of the issue. When I first turn ignition on the fuel gauge starts to move but then drops. I assume the gauge is physically okay and that its some type of electrical issue?

 

Thanks,

Sean

96' c/k1500 (454ss clone w/ 7.4l vortec)

[greatmizzou]

Per the haynes manual you can check a fuel sending unit with an ohmmeter when you remove it.  Watch the voltage change by physically moving the fuel float.  If its not smoothly changing then your sending unit is bad.

 

If it does report smooth changing voltage, then the problem is further up the connection to the dash.  The dash itself has a lot going on that might not be reflecting the incoming data appropriately.  
 

Does everything else otherwise function appropriately, like does it start and run or change fuel level as you drive?

 

It is possible the problem had nothing to do with your sending unit in the first place.  Test the other connections in the circuit and look for bad/open grounds, bad wires, blown fuses, etc

Edited September 7, 2022 by greatmizzou

[Sean Larabee]

_{Thank you for the advice. Everything else functions properly, truck runs great. The only time the fuel gauge ever moves is when you first turn the ignition on (what is shown in the video). It never moves after that.}