Chevy/GM Truck Fuel Sending Units

[TM38]

Greetings All,

Just registered for this first post! I have a neglected 1975 C20 that has served faithfully for over 20 years and it's finally time to get it back in shape and presentable. I have a lot of "new" sheetmetal in the garage but I need to take care of a few mechanical issues first.


Can anyone explain the purpose of the multiple outlets on Chevy/GM fuel sending units? My truck has dual tanks with 2-outlet sending units. I have salvage tanks and sending units from a 1985 model truck that has 3-outlet sending units. The donor truck was recently operational so they should work.

The goal is to replace the passenger side tank, which was disconnected by the previous owner and some of the plumbing removed. If the old sending unit still works I'll just use it and be done with it. But if it doesn't I'd like to use the newer units on both. In either case, the plumbing needs to be replaced and I need to understand how it should be hooked up.

Also, are the newer sending units likely to have the same resistance range
as the older ones?


Thanks in advance,
Tom

[j cAT]

Originally Posted by TM38

Greetings All,

Just registered for this first post! I have a neglected 1975 C20 that has served faithfully for over 20 years and it's finally time to get it back in shape and presentable. I have a lot of "new" sheetmetal in the garage but I need to take care of a few mechanical issues first.


Can anyone explain the purpose of the multiple outlets on Chevy/GM fuel sending units? My truck has dual tanks with 2-outlet sending units. I have salvage tanks and sending units from a 1985 model truck that has 3-outlet sending units. The donor truck was recently operational so they should work.

The goal is to replace the passenger side tank, which was disconnected by the previous owner and some of the plumbing removed. If the old sending unit still works I'll just use it and be done with it. But if it doesn't I'd like to use the newer units on both. In either case, the plumbing needs to be replaced and I need to understand how it should be hooked up.

Also, are the newer sending units likely to have the same resistance range
as the older ones?


Thanks in advance,
Tom

you have 3 lines fuel ,return, and vent.......the diameter size should be different so as to identify whats connected..


because of the age difference I doubt the sending units are the same...also a wiring diagram would be best to use as a guide..