I probably have the answer to this ? in one of my books, but with the eye & sight problems I am having it is just to hard to read anymore, so I thought one of you could answer this. Old Gasser contacted me this morning wanting to know the ohm range of the dash mounted gas & temp gauge for 57 or 58 ford. I hope one of you can answer this and I will relay it to Ron, [Old Gasser] Thanks. Alvin
Hey Alvin. Sorry to hear about your vision issues.
Per Tanks Inc gas gauge/sender info:
73-10 OHMS,for Fords up to 1986. First #=empty, 2nd #= full
Tanks Inc has great troubleshooting/tech info
I don't know anything about the OEM temp gage.
Alvin,
The 1957 Ford shop manual outlines a test for both the fuel and temperature gauges as follows:
1) The Fuel and Temp gauge circuit has a voltage regulator to maintain 5 volts in the circuit. The senders for the gauges then act as resistors to reduce the voltage depending on fuel level and temperature, so the voltage reaching the gauges is modified to vary the reading. When the fuel gauge is at full, it sends 5 volts to the fuel gauge. Temp gauge at hot sends full voltage to temp gauge.
2) The test in the manual for both gauges was to use 2 flashlight batteries in series (each battery has about 1.5 volts) so the two would have 3 volts (new batteries slightly more). You then connect the batteries to the to the gauge terminals which should move the gauge to about 1/2 full (fuel) or 1/2 scale (temp). The shop manual doesn't really give a resistance reading in ohms for the gauges or the senders but from the test description the resistance for senders is highest at empty or low temp and lowest at full or high temp.
Good Luck,
Dave