Talking to Lewis last night in ABCChat, he got a new WEMA fuel sender, but his gauge was still not operating. So, a bit of troubleshooting in order...
First, determine the sender has a good ground. Take your multimeter and put the dial on "Continuity", which on most meters looks like a little horn, and good meters also have an audible signal. Touch one probe (doesn't matter which) on the sender ground wire, the other to a known "good" ground. Get a beep, your good there.
Second, make sure you have continuity on the pink sending wire that runs from the sender to the gauge. You'll probably need a length of wire to act as a jumper, as senders and gauges usually aren't close enough together for the probes to reach both. If you have continuity, then the sender is good to go, time to deal with the gauge.
Third, make sure you have a good ground on the fuel gauge itself. Once again, check for continuity between the gauge ground stud and a known good ground.
Fourth, you need to make sure the gauge itself has power. Now, fuel levels don't work on voltage, they work on resistance to ground. But it IS and electric gauge, and therefore does need 12V. This feed is usually obtained via a jumper coming off the tach or the next gauge physically close to it. The engine harness supplies this power (usually a purple wire), so, with the key switch in the "run" position, check for voltage between the purple (12V+) wire and the black (12V-) wire.
Those are your trouble shooting steps for trying to figure out what is going on with the sender and the gauge. Seeing as the sender is brand new (and, in Lewis' case, a WEMA sender, about the best), if all of the above check out, time for a new fuel gauge. But, I believe Lew's fuel gauge is new as well...
Not that it's the case here, but, if you are installing a new fuel gauge, pay close attention to the markings by the studs on the back side of the gauge. They are marked G (ground), S (sender), and I (ignition power, or 12V+). DO NOT hook up 12V+ to the "S" post, as this will fry the sender in a heartbeat!!
