Resistance specs for fuel and temp sending units?...and other electrical questions

[barsteel]

Hello!

I've posted about my struggle with the fuel and temp gauges in the electrical section of the board, and part of that struggle is trying to find the correct resistance specs for the fuel tank sending unit and the temp sending unit. Yes, I have the manual, but I haven't been able to find it.

Does anyone know the correct resistance range for the fuel tank sending unit and the temp sending unit?

If you're good with gauge trouble shooting, pls check out my post in the electrical section.

Thanks....

Chris

 

[kenmdale]

Fuel and temp resistance is the same, I have the numbers somewhere I will try to find them for you

Cheers
Ken

 

[kenmdale]

Try this thread c-3826 tester for gauges and sensors

Cheers
Ken

 

[Yatzee]

Fuel sender ohmage for pre 1987 Mopars is 73 empty 10 full but strangely enough most after market suppliers recommend 240 empty 33 full. Evidently this ohmage is more accurate as displayed on the gauge due to it's fine increments. I bought a 73/10 and had to incorporate an interface unit and calibrate it for empty/1/2 full and full. It did the rest and filled in the blanks for fuel level. Classic industries SN34. The temp gauge has the same ranges but is even more progressively linear for finer readouts. These senders work off about 5 volts only from the CVU (constant voltage unit) which believe it or not, are not constant but pulse 5 volts about every second as the heater wire uses voltage to open and close an incorporated set of contacts. Go figure.

 

[Lou]

This is way late, but the 10 to 73 sounds right, I measured 12 to 75 ohms on my 65 Fury wagon tank unit about 25 years ago, while patching & red coating the tank. About 3 yrs. ago I replaced the dash temp indicator with one from a parts car, and had to add an aftermarket 5 volt unit to get the fuel & temp gauges working. Then the temp gauge wouldn't read right until I added a loose resistor in parallel to ground with the engine sensor (mounted the resistor on the back of the dash cluster). I had to remove that engine sensor & measure its resistance over the range of temperatures, then calculate a resistance value to add for good readings above 150 degrees. My notes say that the 50 yr. old engine temp sensor read 150 ohms at 50 degrees and 37 ohms at 170 degrees. With the added resistor, the gauge saw 14 ohms at the high end of the normal range on the panel. This agrees with the idea that the temp sensor & gauge work over the same resistance range as the gas gauge, which they have to when using the same voltage source. That extra resistor worked ok at the time, but the car has been parked the last 3 yrs., waiting for me to fix the carb.

I'm getting too old to do this stuff.