working on my 49 ford f1 and having problem with the gauges not registering correctly. I have installed a brand new wore harness and battery running 6v positive ground. Sending units should be good i know for sure my fuel send is good it's brand new. I have existing and I bought a replacement gauge cluster on EBay factory correct model and both existing and new cluster have all gauges not working correctly. Fuel always registers 1/4. Heat register max Hot, oil is about 1/4 or 1/8 on pressure and battery right in the middle. Any ideas I. What is causing the issue? What could be bad that I should try as next step to replace?

 

If you have a V8, there is both a temp sender and a temp switch. If the switch is bad, it will send the gauge to H. It's the sender with 2 terminals.

Right after you start the engine, and rev it up, does the ammeter go to the (+) side?

Have you checked the oil pressure with a mechanical gauge? Maybe your engine is tired and has low pressure?

 

Actually the battery now registers a very slight positive when running. The oil pressure is at 30 in the middle. The temp starts at 1/2 now and moves to full hot while driving although it's not overheating. Fuel stays at a constant 1/4 tank is full.

 

The only person I know who purchased a new reproduction fuel sending unit sent it back since it didn't work.

I would first try the battery test listed in the shop manual to verify if your gauges are good. Then I would ground each gauge sending unit wire to see if each gauges has full travel. Then I would investigate your sending units.

 

Ammeter sounds about right, unless you have a recently rebuilt engine oil pressure reading is probably about right also.
I'm with Ross on the Temp sending unit question and with 38 coupe on the fuel tank sending unit.
BTW, welcome to FTE, you didn't tell us is this truck running the stock engine and fuel tank?