Fuel Guage not working has power 2010 peterbilt 387

You have a wire loose its gonna be on the top back side of your fuel tank. If you got all that fiberglass junk covering your tanks its gonna be hard to get at. You will have to get to it from up under your truck.

 

Check the plugs at the tanks first, clean and replace. Check the sender with a ohm meter, call Peterbilt for the impedance spec.you can also check the gauge the same way by asking for the impedance.

 

You might have water in the fuel level sending unit plug; unplug un dry it out.

 

Fuel sending unit is usually the culprit here. As stated before, check the wiring at the plug, then check resistance on the sender itself. Not a terribly difficult fix to replace the sending unit if that is the problem (which it most likely is), although on our KWs you have to loosen the tank straps, loosen the fuel lines, then rotate the tanks to change it out.. that in itself isn't such a daunting task, although it is a bit of a PItA.