I have a 72 F100 with a 390. The owner before me made some "improvements". He installed a set of 3 Sunpro gauges and removed the connections from the instrument panel. A couple of questions and I apologize for the elementary questions.

1) How does the temp guage attach to the back of the instrument panel. It is currently on the end of a flexible cable and screwed into the back of the Sunpro gauge.

2) The oil pressure gauge has the plastic line running from the top of the oil filter housing to the back of the gauge. How does this connect to the instrument panel. I do not see any place it would connect.

I may be missing parts or brain cells but am stumped.

Thanks

Shawn

 

Your original gauges are electric and the gauges the PO put in are mechanical. The electric gauges need sending units put into the motor whereas the mechanical gauges don't.

The electric gauges work from the sending units providing an amount of grounding; in other words when the motor isn't running it has no oil pressure so the oil pressure gauge doesn't move. When you start the engine and it's idling it will provide some grounding to the gauge because the sending unit is having oil pressure applied to it and it's starting to signal the gauge. Rev the motor up and it provides even more grounding to make the gauge read higher. Shut the engine off, take the wire that should go to the sending unit and ground it to the block and it will peg the gauge.

No telling what happenned to the wiring harness, but the way the wires were originally routed from the factory was the temp and oil sending unit wires ran from the back of the dash thru the hole in the firewall just above the throttle linkage, and out to the front of the motor on the driver's side along with the coil wires.

 

I knew they had to convert to electrical somehow. Thanks for your help. I will just keep the mechanical guages for now. Now, time to put the new stereo in