Faulty Fuel Guage Diagnosis?

Do a search on this forum, there are tons of threads about gauge problems


The Mopar test box is basically a resistor substitution box. You can buy some resistors at Radio Shack and hook them in place of the sender. Both temp, fuel (and oil in some cars) are the same resistance, so one set of three resistors can check all three gauges.

Full is about 10-11 ohms, 1/2 is 23-25 ohms, and empty is about 73 ohms

For example, for the 1/2 scale, buy a pack of four - 100 ohm, 1/2 watt resistors at radio shack. Wire all 4 in parallel, which will then be a 25 ohm, 2 watt resistor, in effect. Buy a bag of clip leads while you are there. Cut three of them in half, and solder "a half" a clip lead to each of your resistors.

Hook one resistor at a time from the sender wire connection to ground. You can try this with the temp, first, as it's easy to get to. Check with engine running, and give it "a minute" for the gauge to fully stabilize.