Isuzu Cars and Trucks 1981-1991

Mechanical Fuel Pump

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REMOVAL AND INSTALLATION
G180Z and G200Z Engine with Mechanical Pump

The fuel pump is located beside the distributor at the right, front side of the engine.

  1. Relieve the fuel pressure.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Mark the distributor rotor and housing location before removing distributor. Remove the distributor cap, with the wires attached and the distributor assembly.
  6.  
  7. Disconnect and plug the fuel lines from the fuel pump.
  8.  
  9. Remove the engine hanger.
  10.  
  11. Remove the fuel pump-to-engine bolts and remove the pump assembly.
  12.  



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Fig. Mechanical fuel pump

To install:

  1. Using a new gasket, install the fuel pump on the engine.
  2.  
  3. Install the engine hanger.
  4.  
  5. Unplug and connect the fuel lines to the fuel pump.
  6.  
  7. Install the distributor and the distributor cap.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Start the engine and check for fuel leaks.
  12.  

4XC1-U Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Relieve the fuel system pressure.
  4.  
  5. Disconnect the fuel hoses.
  6.  
  7. Remove the retaining bolts, pump and gasket.
  8.  



Click image to see an enlarged view

Fig. Fuel pump 4XC1-U engines

To install:

  1. Clean the gasket mating surfaces and install the pump with a new gasket.
  2.  
  3. Tighten the retaining bolts.
  4.  
  5. Connect the pump hoses and negative battery cable.
  6.  
  7. Start the engine and check for leaks.
  8.  

4ZD1 Carb. Engine

The fuel pump is located at the right side of the engine, directly under the intake manifold.

  1. Relieve the fuel pressure.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the air cleaner assembly.
  6.  
  7. Remove the intake manifold assembly.
  8.  
  9. Disconnect and plug the fuel lines at the fuel pump.
  10.  
  11. Remove the fuel pump-to-engine bolts and the pump assembly.
  12.  

To install:

  1. Remove the cylinder head cover.
  2.  
  3. Rotate the engine to position the No. 4 cylinder at TDC.
  4.  
  5. Lift the fuel pump pushrod toward the camshaft and hold it in the raised position.
  6.  
  7. Using a new gasket, install the fuel pump on the engine; torque the bolts to 1525 ft. lbs. (2034 Nm).
  8.  
  9. Connect the fuel hoses to the fuel pump.
  10.  
  11. Using a new gasket, install the intake manifold.
  12.  
  13. Install the air cleaner assembly.
  14.  
  15. Connect the negative battery cable.
  16.  
  17. Start the engine and check for fuel leaks.
  18.  



Click image to see an enlarged view

Fig. Fuel pump and pushrod 4ZD1 carb. engine

TESTING
  1. Remove the fuel pump from the vehicle.
  2.  
  3. Check the outside of the pump for cracks, leakage and other damage, replace if necessary.
  4.  
  5. Check for excessive wear between the rocker arm and camshaft contact surfaces.
  6.  
  7. Check the inlet valve by moving the rocker arm to the pump side and hold it in this position. Shut both the return and outlet pipes with your fingers. When the rocker arm has returned to its original position, there should show a marked increase in the amount of play. If no increase, replace the pump.
  8.  
  9. Check the outlet valve by closing the inlet pipe. The rocker arm must not move when the pipe is closed. Do not use excessive force.
  10.  
  11. Check the diaphragm. The rocker arm must not move when the inlet, outlet and return pipes are shut, if so replace the pump.
  12.  



Click image to see an enlarged view

Fig. Checking the fuel pump

 
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