[slumlord44]

Oil pressure gauge works fine. Gas gauge works. Gave up on amp guage. Temperature gauge is the problem. When engine starts to warm up guage goes all the way to hot. Stays all the way to cold until engine warms up. Tried different sending units and two gauges. Short the wire to the sending unit to ground and it goes all the way to hot. which indicates gauge is ok per shop manual. Pull the sending unit from the engine, hook up the wire to the gauge and ground the sending unit and it stays on cold until you heat it up. Hold the sender between my fingers and as soon as it warms up to body temp it goes all the way to hot. The fact that the gas guage works tells me that the constant voltage regulator is working. What am I missing here? Tried two used sending units and a new one. Same results. Sending unit seems to act as an on off switch.