gas gauge

[WILLIAM S FLYNN]

gas Guage is pinned passed full forever, it used to work, I had a temporary cluster while mine got recalibrated from Alanta speedo, it had been rebuilt corrected the MPH ,Clocked my miles and new bulbs with all gauges tested and functioning .i put a new Delphi sending unit in ,made sure all connections and ground wire was clean.
question: can i jump a wire from about sending unit up to fire wall before the fire wall . ,I've tried grounding the wire in another spot ,frustrating i know its the purple wire .

weird i past washing engine bay the gauge would act up .I've owned this 1997 Silverado for 21years.
any guidance is apricated

 

[pieceofchevy]

i am working on a 1988 chev c3500 and neither gas gauge works. i need a wiring diagram for the gauge. tried the link under wiring diagrams and nothing happened.

 

[Tommy1234]

I looked up diagram stuff and I couldn't find any and I need help too