Isuzu Cars and Trucks 1981-1991

Electric Fuel Pump

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PRESSURE TESTING
  1. Relieve the fuel pressure.
  2.  
  3. Disconnect the fuel line near the engine and install fuel pressure gauge T-connector in the line.
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  5. Connect the fuel pressure gauge to the T-connector.
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  7. Start the engine and check the fuel pressure, it should be:
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  9. 1981 I-Mark G180Z 2.43.3 psi, carburetor inlet hose.
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  11. 4XC1-Turbo and DOHC I-Mark, G200Z Impulse: 35.6 psi with the vacuum hose of the pressure regulator disconnected and plugged. 28.4 psi with the vacuum hose connected and at idle.
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  13. 4ZC1-Turbo, 4ZD1 Impulse and 4ZE1 engine: 42.6 psi with the vacuum hose at the pressure regulator disconnected and plugged. 35.6 psi with the vacuum hose connected at idle. Disconnect the VSV before checking pressure.
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  15. V6 engine: 913 psi at the fuel pressure line after the fuel filter.
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  17. 4XE1 SOHC and DOHC engine: Flow test, disconnect the hose from the EFI fuel feed line at the engine and place in a suitable container. Apply battery voltage to the fuel pump. Pump should supply 1 / 4 quart (0.24L) within 15 seconds. Pressure test, connect a pressure gauge in the fuel pressure line after the fuel filter, located at the driver's side frame rail. Disconnect the vacuum hose from the pressure regulator. Apply battery voltage to the pump. After the pump stabilizes, the pressure should be 35 and 1938 psi (245 and 19256 kPa) and hold steady.
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REMOVAL AND INSTALLATION
1981 I-Mark, G180Z Engine

The 1981 I-Mark has an electric fuel pump located in the rear of the vehicle. Disconnect the negative battery cable and release the fuel pressure. Disconnect the fuel lines and electrical connectors. Remove the retaining bolts and pump.

In-tank Fuel Pump

NOTE
Fuel is under high pressure, if the following steps are not followed the fuel could spray out and result in a fire hazard or possible injury. The fuel pump is located inside the gas tank.

  1. Relieve fuel pressure then disconnect negative battery cable.
  2.  
  3. Raise and support the vehicle safely. Drain fuel tank. Remove the undercover screws and undercover, if so equipped.
  4.  
  5. Remove all gas line hose connections and fuel pump ground wire.
  6.  
  7. Remove filler neck hose and clamp.
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  9. Remove breather hose and clamp.
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  11. Disconnect fuel tank hose to evaporator pipe. Place a suitable floor jack with a piece of wood on it under the fuel tank.
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  13. Remove fuel tank mounting bolts and lower tank from car. At this point remove hose from pump to fuel filter.
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  15. Remove fuel pump bracket plate and fuel pump as an assembly.
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  17. Remove pump bracket, rubber cushion and fuel pump filter.
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Click image to see an enlarged view

Fig. Exploded view of the electric fuel pump except V6 engines

To install:

  1. Install the pump to the bracket and rubber cushion. Install the fuel pump filter.
  2.  
  3. Install fuel pump bracket plate and fuel pump as an assembly.
  4.  
  5. Raise the tank and connect the hoses. Tighten the tank straps.
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  7. Connect fuel tank hose to evaporator pipe.
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  9. Install the breather hose and clamp.
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  11. Connect the fuel pump ground wire. Install the undercover and screws.
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  13. Lower the vehicle safely. Refill fuel tank and check for leaks.
  14.  
  15. Connect negative battery cable and check operation.
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