Hi,

I'm replacing the passenger side tank on my 1975 C20. The sending unit in the old tank is dead. The sending unit on the "new" tank  from a 1985 truck ranges from about 15 ohms empty to 130 ohms full. Does this make sense? I can't seem to find any definitive information on the required resistance range for these units. I'd like to use the sending units from the newer tank.

It's interesting to note that when the driver side tank is selected, the fuel gauge reads about a quarter tank too full at all times, ie overfull after fill-up, and the truck runs out of gas reading a quarter tank.

What are the expected ohm ranges for 1975 and 1985?

Thanks,
Tom  

LMC list them the same from73-87 but don't give the ohms. Sounds to me that you have somethin else going on like a short or something.
You might try a Chevy dealer of find a manual.  

Well, I'm not sure what the resistance ranges is "supposed" to be, but I can confirm that they are the same from the two trucks. I hooked up the newer sending unit to the fuel gauge in the truck and it gave the same readings.

I do have some other problem though. I think it may be the selector switch.

Tom  

Tanksinc.com Give them a call they should know.