Toyota Corolla 1988-1997 Repair Guide

Mechanical Fuel Pump

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REMOVAL & INSTALLATION



See Figures 1 through 8

  1. Disconnect the negative battery cable.
  2.  



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Fig. Fig. 1: Cutaway view of the mechanical fuel pump

  1. With the engine cold and the key removed from the ignition, label, disconnect and plug the fuel lines from the pump.
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Fig. Fig. 2: Always label the hoses leading to the fuel pump prior to removing them



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Fig. Fig. 3: Slide the hose clamps far enough to pull the hoses off the pump



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Fig. Fig. 4: Remove the hoses connected to the pump. Make sure a rag is handy for spilt fuel



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Fig. Fig. 5: Unbolt the fuel pump from the engine

  1. Unscrew the two fuel pump retaining bolts. Remove the fuel pump, gaskets and insulator.
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Fig. Fig. 6: Separate the fuel pump from the engine ...

  1. Inspect the insulator for any cracks or damage. Replace if necessary.
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Fig. Fig. 7: ... then pull the insulator and gaskets from the pump and mating surfaces

  1. Cover the mating surface of the cylinder head where the fuel pump sits to prevent dirt entering.
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To install:
  1. Place new gaskets on either side of the insulator. Insert the pump arm through the hole of the insulator/gaskets and mount on the engine. Tighten the two mounting screws to 13 ft. lbs. (18 Nm).
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Always use new gaskets when installing the fuel pump.

  1. Reconnect the fuel lines.
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  3. Connect the negative battery cable.
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  5. Start the engine and check for any leaks.
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TESTING



See Figures 8, 9, 10 and 11

Before performing and checks on the fuel pump, two conditions must be met. First, the pump must be internally "wet". Run a small amount of fuel into the pump so that the check valves will seal properly when tested. Dry valves may not seal and will yield false test results.

Hold the pump with out blocking either pipe and operate the pump lever, noting the amount of force needed to move it. This is the reference point for all tests. Do not apply more than this amount of force to the lever during the testing. Excessive force can damage an otherwise useable pump.



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Fig. Fig. 8: Checking the inlet valve on the fuel pump

  1. Block off the outlet and return pipes with your fingers. Operate the lever. There should be an increase in arm play and it should move freely.
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Fig. Fig. 9: Checking the outlet valve on the mechanical fuel pump

  1. Block the inlet port with your finger and operate the lever. The arm should lock when the normal amount of force is applied.
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  3. The diaphragm is checked by blocking the inlet, outlet and return pipes. When normal force is applied to the lever, the lever should lock and not move. Any lever motion indicates a ruptured diaphragm. This is a common cause of poor fuel mileage and poor acceleration since the correct amount of fuel is not being delivered to the carburetor.
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Fig. Fig. 10: The diaphragm is checked by blocking the inlet, outlet and return pipes

The fuel pump must pass all three of these tests to be considered usable. If the pump fails one or more of these tests, it must be replaced.

  1. Check the oil seal within the pump. Block off the vent hole in the lower part of the pump housing. The lever arm should lock when normal force is applied.
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Fig. Fig. 11: Inspecting the oil seal within the pump

 
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