Fuel Gauge DiagnosisA very common problem with old VW’s is a faulty, worn or varnished fuel sending unit. If your fuel gauge is going haywire (or refuses to move), there are some simple checks and repairs that you can do yourself to get it working again.
Below are the models, years, and the senders that apply.
62 to 67 beetles and 62 to 66 Ghia’s were equipped with a mechanical fuel sender. These were the simplest and most trouble-free of all the years. They did have their own set of problems though…. The gauge and cable need periodic adjustment and lubrication, the boot around the float can swell and leak over time, and the cable that operates the gauge can suffer from damage.
67 to 73 Ghia’s and 55 1/2 to 67 busses were equipped with a tube style electrical fuel sender. Somewhat like the later, but these type are completely unserviceable. Follow the inspection procedure below for these models.
68 and later beetles, 74 and later Ghia’s, busses and Things were equipped with a lever style fuel sender. These senders are usually easy to clean, troubleshoot and repair.
# 1) Before working on any part of your fuel system, disconnect your battery, and please don’t smoke!
# 2) Acquire a new gasket before removing the sender. 
# 3) The tube and lever style can be easily checked with an OHM Meter. Remove the wires, and then slowly remove the sender while being careful not to drop any of the hardware in the tank. Hook the 2 probes of the OHM meter to the sender terminal and the body of the sender. Work the sender up and down, while looking at the readings. The readings should slowly and smoothly increase/decrease as you move the float up and down. You are looking for dead spots (the meter will go to zero), and non- sequential numbers on the meter.
#4) If you find any of these issues, and you have a lever style sender, you can try to clean the contact surfaces of the contact plate. Just spray a little carburetor cleaner on the surface and carefully scrub with a small brush. Fuel tends to gum up in this area, due to more exposure to air by not always having a full tank of fuel. Many times this can revive an old and otherwise dead sender.
#5) If your electrical gauges needle jumps around, it is most likely that your “vibrator has gone bad". The Vibrator is a device that is mounted to the speedometer, behind the fuel gauge, and smooth’s out the signal from the sender.
#6) If the needle jumps to full and back or is just stuck on full, it is due to a bad or partial ground between the body of the gauge and the back of the dash. THe quick fix is to loosen the mounting screws on the back and wiggle the mounting leg(s) back and forth to cut through any rust, paint, etc, that could casue a bad ground, then re-tighten
#7) Vibrators and Senders are readily available at Airhead Parts.
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