The gauges in my 67 F100 stock 352 behave like this.
-Oil Pressure Gauge: Reads near to high side at start up and doesn't change as engine warms up or RPM increases. I removed the sending unit and tested using an oil pressure gauge. Pressure seems good and increases with RPM increase.
-Temperature Gauge: Goes all the way over to near "H" in a couple of minutes after starting and doesn't move in different traffic conditions, speeds or outside air temperature. When I check various locations on the engine, rad and hoses, with an infrared gun, right after a drive I get what I believe are reasonable numbers, recognizing that they are likely 20 degrees or more below the coolant temp.
-ALT gauge: pegs at centre and never seems to move.
-Fuel gauge: seems quite accurate.

I came across this gauge tester on the web, and wondered if anyone has any experience using it.
I think my Instrument Voltage Regulator is likely OK since the gauges do move, but would like to test the gauges for calibration before doing anything with them and this seemed like a good way without accessing them directly.

 

You can test your water temp sender by heating up some water and dropping the sender into it.

the gauges all use the same power source so I would think if the gauge voltage regulator was bad all the other gauges would be wrong.

 

73 f250 4x4...
My ammeter gauge is the only 1 working. Water temp, oil pressure and fuel not working. Any ideas how to test gauges? When I started this project I tested and bought "new" gauges if they didn't test out. Now 2 years later finally got truck running and they not reading..

 

What have you done so far?

I think the ammeter is it’s own wiring circuit. The others use a voltage regulator. The wiring diagram should help.

 

You are right only the oil / temp / fuel use the IVR behind the dash.
I would guess if 2 of the 3, not sure on the fuel?, the IVR is bad and would replace it.
When doing so I would remove the printed board and use some vary fine sand paper and sand all the contact points for the gauges, IVR and the plug.
You may want to run a ground wire from the cluster to a good body ground.

This brings out other things. Being the 2 gauges not working are on the motor I would go over all the grounds on the truck.
Battery to motor, motor to frame, motor to cab firewall.
Dont just look at them and say "they look good" as that will not cut it.
Dave ----

 

First I would pull all fuses and clean the holders & fuse ends as they sometimes get a crust and stop working.

To see if the 3 gauges work is easy, take the sender wires and put them to ground.
Turn the key on or with the key on and someone watching the gauge put the wire to a good ground.
The gauge should move up to max. DO NOT hold it to MAX long as it could hurt the gauge.

The other thing you can do is take a old test light, non LED, and hook it to a good ground and then with key on touch the sender wire.
If wiring is good the light should blink.

Little back ground the IVR gets power when the key is on this regulator turns on & off power, the blinking, to maintain about 6 volts.
You can use a old analog meter to check this the new digital meters can not really see this 6 volts as it reacts to fast to the on / off.

If the light dose not blink or the gauges do not move and the fuses are good I would then pull the cluster to see if the IVR is getting power of 12 volts and if 6 volts out. If yes then I would say bad oil / gas / temp gauge.

1 other thing I dont know how the wire harness passes from inside to the engine bay but if it bolts together at the "bulk head" they have been known to get crud between the 2 halves so check it also.
Dave ----