This was posted in Dec. 2017, 10 months ago and has over 700 "reads". Tells me instruments are a topic of interest. I just got my ol' 1974 B back and have trouble with the gas gauge not registering, so I installed a new sending unit. Simple, and the float in the old sender had gas in it. Thought I had solved the problem, but the gauge still wouldn't register. Removing the new sending unit I found gas in the NEW plastic float. There is a small crack on the shoulder of the groove where it fits in the wire arm. I manually operated the arm of the sending unit, the new gauge registered no more than a half tank. Too much resistance in the wire between the gauge and the sending unit? I will try a new connector. Ordered a new brass float, but why doesn't the sending unit allow the new gauge to register full? With about 6 gallons of gas it registers a quarter. Now I am thinking it may have one of those new, larger tanks! When I re-reinstall with the new float, I will fill it up and see how much it takes and what it registers, and measure the volts from the voltage stabilizer to see if it is putting out a full 10 Vts. But the speedometer is wildly optimistic! At 65 MPH per a GPS, the speedo registers 80 MPH! The speedo is not connected to the voltage stabilizer. Must I send the speedo out for calibration?
Replaced leaking plastic float #2 with a brass one, tightened the connector, and its registering about the amount of gas it should, at over 1/2 tank. (I checked voltage to the fuel gauge and its just over 9.9 volts.) Fixed for now! Lesson, don't trust those plastic floats. Speedo is still overly optimistic.