Volkswagen Air Cooled 1949-1969 Repair Guide

Sending Unit

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TESTING & REPLACEMENT




WARNING
Gasoline vapors are EXTREMELY volatile. To prevent the potential danger of spilled gasoline, drain the fuel tank with a hand pump siphon prior to removal. When servicing the fuel system: extinguish all open flames, do not smoke, have a fire extinguisher handy at all times, and always ensure proper ventilation of fresh air in the service area.

  1. Disconnect the negative battery cable.
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  3. On type 2 models, remove the fuel tank from the vehicle.
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  5. Label and detach all electrical wiring from the sending unit.
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  7. To test the sending unit while it is installed in the vehicle (on type 2 models this is impossible), perform the following:
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    1. Connect an ohmmeter to the sending unit. Connect the negative lead from the ohmmeter to the sending unit metal housing and the positive lead to the lead wire terminal connector on the top of the sending unit.
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    3. If the sending unit displays infinite resistance, the sending unit is bad and must be replaced with a new one.
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    5. If the fuel tank is partially empty, the sending unit can be further tested while installed by slowly filling the fuel tank with gasoline until full. While filling the tank, watch the ohmmeter value. The resistance value should change smoothly. If the reading does not change or changes erratically, replace the sending unit with a new one.
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  9. Remove the five sending unit mounting bolts, then carefully lift the unit up and out of the fuel tank. Remove the old sending unit gasket.
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  11. If not already done, test the sending unit as follows:
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    1. Connect an ohmmeter to the sending unit. Connect the negative lead from the ohmmeter to the sending unit metal housing and the positive lead to the lead wire terminal connector on the top of the sending unit.
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    3. If the sending unit displays infinite resistance, the sending unit is bad and must be replaced with a new one.
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    5. If the sending unit shows anything but infinite resistance, slowly tilt the sending unit upside-down and watch the ohmmeter reading. (Tilting the sending unit upside-down moves the float arm) The resistance value should change smoothly. If the reading does not change or changes erratically, replace the sending unit with a new one.
    6.  

  13. Installation is the reverse of the removal procedure. Be sure that the rubber gasket is positioned correctly. The ground lug on the sending unit must be able to slip through the cut out in the gasket and make contact with the fuel tank. The fuel tank should be clean and bright where the ground lug contacts it.
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