Thread: fuel sending unit MELTED

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The original instrument voltage regulator is a vibrating type. As the current flows through the thin wire wrapped around the arm, it heats it up. Being a bimetallic strip, this causes the arm to bend, breaking contact, which allows it to cool, starting the cycle over again. It does this continuously, with an average voltage of about 6 volts. The only way it can fail is with a short downstream, which causes the fine wire to act as a fuse, burning it in two.

Unfortunately, mine failed sending full 12 volts.

Upon examination, I found the fine wire had shorted to case, and welded itself to the case, without burning in two.

Originally Posted by enjenjo

The original instrument voltage regulator is a vibrating type. As the current flows through the thin wire wrapped around the arm, it heats it up. Being a bimetallic strip, this causes the arm to bend, breaking contact, which allows it to cool, starting the cycle over again. It does this continuously, with an average voltage of about 6 volts. The only way it can fail is with a short downstream, which causes the fine wire to act as a fuse, burning it in two.

With this in mind would it be a smart move to build a voltage divider, solid state and eliminate that weak point. If the circuit is fused that would give you the load required.

In the 50s car radios were AC because of the tubes; they had a component in the radio called a multi vibrator. It would act just as you described producing AC, a half sign wave. It is strange they would use this same technology in what I think is a pure DC circuit. Jest saying how it looks ..

Could it be that the component he is holding in post # 14 is really a Fred Flintstone self-resetting circuit breaker ( voltage regulater ), and the fact the he found it shorted could cause the sender to fry? With all the problems he is having I would, if it were me, ring out the wiring from the gage cluster to the senders. Simply remove the wire from the cluster side and the sender let them float, check for a ground on the wires with a meter.

I can definitely ground check the wires off the gauges, too easy. I like the idea of fusing the solid state voltage reducer. I'll have to figure out what size fuse.