All gauges aren't working on my 71 Road Runner (except the amp meter, it works okay). Pulled the sending unit to test it with a cheap harbor freight multimeter. What range should i set it to & what should it read?

I set it to 2000 ohms and it appears to be reading from about 15-73 throughout the float range. It's the original unit & I assumed it would be bad, but now I'm not so sure.

W temp and gas gauges both not working that'd point to the voltage limiter, a small metal component on the back of the dash printed circuit going bad or an open & VL's are problematic & not likely that the wide copper printed circuit went open to both gauges from the VL. I'd prob drop the col a bit & pull the dash out enough to access its' backside & ohm it EDIT w a jumper wire connect the sender flat metal to the fuel line and blue hot wire plugged in have a helper see if the gauge needle swings toward F as you raise the float (key on). If it stays on the left side of E the prob ain't the sender but make sure you have it grounded for a valid test

15 to 85 ohms on the fuel sending unit.

If that voltage limiter goes bad it could fry all the gagues, i put a electronic one in mine.

on my '69 B-body, it was the pins on the back of the printed circuit board...you know; the BIG round plug on the back of the cluster...wiggle it around a bit and see if the gauges start working. if so, it's resolder the pins or replace the board.

Im fighting the same problem on my car right now both gauges do not work. Im going to get a voltage limiter today but here is a good article I found during my search.

http://www.moparfins.com/repairs/fuel_gauge_repair/fuel_gauge_repair.htm

Hope this helps

If you have soldering skills look up the solid state regulator conversion. Computers ued a 5VDC power supply and it is available on a chip.
It's much better than the original regulator that used dome sort of contacts that opened and closed to create an "average" 5 volts.
R.