have you checked the fuel gauge itself to make sure it is working
how to install the oil pressure gauge on a Chevy 350 small block
Test it with a vacuum gauge.
Check your fuses, if ok..You need to replace the sending unit for this gauge.
Check your fuses in your fuse block you should have a fuse that says "gauges". If you fuses check good take it to a mechanic shop.
Check the switch.
Check the float by pining the wiring at the tank the gauge will go to full if not the wiring or gauge may be defective
One of the gauges or wiring has shorted to ground.
It's not fused separately. If your fuel gauge isn't working, you either have faulty wiring to the gauge, or a faulty fuel sending unit.
If you find the wire to the switch near the thermostsat.Then earth the single wire to the engine and if the gauge inside lifts to max then the wiring and gauge are ok, then its def your switch. Check your fuses for your gauge and check condition of wire coming from temp sensor on block. Sometimes they come disconnected or break from heat.Check continuity from gauge to sensor,if none replace sensor.
the purple wire is the gauge and white and black are ground!
Right above the oil filter.
There is a 1/8"npt port on the back rail of the block near the distributor hole.