Sending unit/gauge match up.

I'll be pulling the gas tank in my Jeep within the next few weeks and I was wanting to fix the sending unit and/or gas gauge while it is out. I was told by the PO that the ohms on sending unit don't match the ohms on the gauge. So, what would be easier, getting a new gauge to match the sending unit, or just get a new matched gauge/sending unit while it's pulled?

Are the sending units pretty much standard in Jeeps? The tank in my M38-a1 is out of a 70's CJ5.

Thanks

Dondo

 

I use the original M38a1 sending unit with an Autometer fuel gauge. Shouldn't have too match the sender to the gauge.

 

You have to match the sender to the gauge. Here is a list of some common values (from the VDO site I think):

Stewart Warner sender, 240 - 33 Ohms (most common aftermarket)
VDO sender 10 -180 Ohms
Beetle O.E. sender 73 -10 Ohms
GM sender (from 1965) 0 - 90 Ohms
GM sender (until 1965) 0 - 30 Ohms
Ford/AMC sender (up to 1986) 73 - 10 Ohms
late model Ford, (1987 and up) 16 - 158 Ohms

Trying to match a new sender to an old gauge can be tricky. Not only does the ohm range have to match, but the gauge's full/empty to sender's hi/low ohms relationship has to match as well. If the gauge is "looking" for 10 ohms empty, but your sender reads 10 ohms full, it won't work.

Original Jeep gauge wants to see 73 ohms empty, 10 full. The general standard for aftermarket "universal" gauges for auto and marine (boating) is 240 ohms empty, 33 ohms full. You can get a "universal" 240-33 sender kit from NAPA that can be adjusted to fit most tanks, but you'll have to use the gauge in the kit (or any other 240-33 gauge) to make it work. And regardless of what sender/gauge combo you want to use, you must give the gauge and sender good grounds!

Stan