62 Impala sending unit

26Jul 2017
kevin coakley
I purchased a new sending unit from CarsInc some time ago for my 62 Impala. The fuel gauge in my car doesn't seem to be working. In addition to the new sending unit I also installed a new chassis wiring harness. I'm currently measuring 6v on the power wire to the gauge and 60 ohms of resistance from the sending unit. The tank is full BTW Does this seem correct? The research I've done on line seems to indicate I should be getting 12v with 30 ohms resistance.

27Jul 2017
Mr Bowtie
Kevin Coakley, Most common cause of fuel gauge trouble is high resistance in the circuit usually caused by dirt, corrosion or paint. 30 Ohm resistance in 1961-4 Impala sending units. Many times, when a car is restored there is new, heavy paint where the ground wire attaches. Ground wire requires clean, rust free, dirt free, corrosion free, paint free metal contact. Without good ground the fuel gauge will not complete the circuit. Have step by step instructions to check the sending unit as well as the gauge in the tank if you need these please advise.
28Jul 2017
Kevin Coakley
I would appreciate if you could provide the instructions. Thank you.
29Jul 2017
Mr Bowtie
TEST THE IN DASH FUEL GAUGE 1. Loosen the wire from the fuel sending unit on the gas tank. Make certain it doesn't touch anything. 2. Turn the ignition switch to the "ON" position. 3. The gauge should go to or past the full mark. 4. Turn the ignition switch off. 5. Using the sending unit gauge wire you loosened, ground it to the frame. 6. Turn the ignition to the "ON" position. 7. The gauge should read empty or below. 8. If the gauge reads correctly, the gauge is working properly. 9. If the gauge does not read correctly, replace the gauge CHECK FOR GROUNDING PROBLEMS WITH FUEL TANK SENDING UNITS 1. Most of the problems with the sending unit gauge system are caused by inadequate grounding. 2. If the system is not grounded properly at the fuel tank, the in dash fuel gauge will not operate properly. 3. When restoring the car, many times the under body is painted or coated heavily with primer. The gas tank is clear coated to keep it looking nice and the gas tank attaching straps are painted. All of these can cause bad grounding problems. 4. From the factory these cars, 1961-4 Chevrolet's, were not painted heavily in these areas. They relied on grounding between the gas tank, the body and the attaching straps. 5. If grounding is the problem, you can make a short ground wire and attach it from one of the screws on the gas tank sending unit to the body of the car.

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