Can I use the factory sending unit with a aftermarket fuel guage? Or do I have to use the sending unit that came with the guage? 67 Camaro.
Thanks

 

So I decided to see if I cant use the old sending unit and here is what I got. Tank empty ohms reading 9, guage shows full. Tank full ohms reading 90, guage shows 1/2 full. Why is this backwards? And why wont it go all the way to empty on the guage?
Thanks

 

The sending unit and the gage have to be matched.

 

So now the problem is where to mount the aftermarket sending unit. Cant mount it in the same place as the old one because of the pick up tube and to mount it anywhere else on the top of the tank would allow the sending unit to bottom out on the trunk floor.
Thanks

 

What brand gauge are you using?

I was just one the Autometer site and I always thought you had to use a sending unit to match the gauge, but it looks like as long as you have the correct Ohm's for the gauge it should work with the factory sending unit.

For GM it should be 0-90ohms with 0 being empty and 90 being full.

You confirmed you got the correct ohm's, but is the gauge right for that?

 

GM sending unit resistance reads near or at zero ohms when empty, 90 when full (as yours is). But Ford and Chrysler are the opposite. Sounds like your gas gauge isn't one that's compatible with GM's system.

 

Camaro 69 you are right the guage I have is not compatible. It turns out its a 240 to 33 ohms. Now I need to decide whether to buy a new guage or use the sending unit that came with the guage. Its a Classsic Instument guage. Thanks for your help.