Finally-a working fuel gauge...
Posted: Fri Jan 09, 2015 2:41 am
When I got my 12V vintage gauge set from Auto Meter I retained use of the M37's fuel sending unit since it was new. Once the gauges were installed, the fuel gauge was all over the place-full, then half full, then empty, then back up. In other words, never stable, and it finally pegged on "full" as soon as it powered up and never changed. Since I carry fuel in the spare jerry can I lived with the jumping gauge, until today.
I realized that my gauge set likely included a fuel sending unit so I dug up the box and found the sending unit under the gauge retaining panel. Since we had a 45 degree day today I tackled the install. The new sender had the matching bolt pattern so I followed the instructions then attempted to drop in the unit. Surprisingly, it did not fit, and I ended up trimming some of the rheostat housing and the mounting bar down so I could work it in. That took an hour, then I moved to the wiring which took no time, then powered up. The gauge read low at around 1/4 tank when I had around 2/3 in it. So, after removing, adjusting, trimming the float arm and the rheostat height then re-installing at least a dozen times (and eventually making it a hybrid by using the M37's brass float and arm on the Auto Meter Rheostat) I finally got the accurate reading at just under 2/3 of a tank. I finalized the work at around 3 hours (after I only expected an hour at best), but the gauge now reads accurately and steady w/o jumping all over the place.
So, in summation, my 12V gauge wouldn't work with the M37 sender, and my follow up research indicates that the Ohm ratings vary on different manufacturers' equipment so it's best to purchase the matching sending unit for your gauge.
Glad to finally have a full set of working gauges (sorry, no pix on this project)!
Gary
I realized that my gauge set likely included a fuel sending unit so I dug up the box and found the sending unit under the gauge retaining panel. Since we had a 45 degree day today I tackled the install. The new sender had the matching bolt pattern so I followed the instructions then attempted to drop in the unit. Surprisingly, it did not fit, and I ended up trimming some of the rheostat housing and the mounting bar down so I could work it in. That took an hour, then I moved to the wiring which took no time, then powered up. The gauge read low at around 1/4 tank when I had around 2/3 in it. So, after removing, adjusting, trimming the float arm and the rheostat height then re-installing at least a dozen times (and eventually making it a hybrid by using the M37's brass float and arm on the Auto Meter Rheostat) I finally got the accurate reading at just under 2/3 of a tank. I finalized the work at around 3 hours (after I only expected an hour at best), but the gauge now reads accurately and steady w/o jumping all over the place.
So, in summation, my 12V gauge wouldn't work with the M37 sender, and my follow up research indicates that the Ohm ratings vary on different manufacturers' equipment so it's best to purchase the matching sending unit for your gauge.
Glad to finally have a full set of working gauges (sorry, no pix on this project)!
Gary
i've gotten pretty good over the last decade at judging how much gas is in the tank by knocking on it. only ran out of gas once.... on a bridge 