Jeep Wrangler/YJ 1987-1995 Repair Guide

Fuel Pump

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TESTING



Pressure Test

See Figures 1 and 2



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Fig. Fig. 1: TBI pressure test port plug-1987-90 with 2.5L engine



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Fig. Fig. 2: TBI pressure adjustment-1987-90 with 2.5L engine

The fuel system on vehicles equipped with Throttle Body Injection (TBI) is only under pressure when the fuel pump is operating. As long as the fuel pump is not operating, the TBI fuel system components can be removed without the need to release the fuel system pressure.

Fuel pump operating pressure is 14.5 psi (100 kPa). The fuel pressure regulator is adjustable by means of a Torx® head screw on the bottom of the pressure regulator.

  1. Remove the air cleaner assembly. Remove the screw test port plug on the throttle body, then install a fuel pressure test fitting. Pressure test fittings are available at many auto parts stores.
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  3. Connect an accurate pressure test gauge to the test fitting.
  4.  
  5. Connect a tachometer to diagnostic connector terminals D1-1 and D1-3, then start the engine and accelerate it to 2000 rpm.
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  7. Read the fuel pressure on the gauge. If necessary, turn the adjustment screw on the bottom of the fuel pressure regulator to obtain 14.5 psi (100 kPa) of fuel pressure. Turning the screw inward increases the pressure and turning the screw outward decreases the pressure.
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  9. Once all adjustments are complete, install a lead seal ball to cover the regulator adjusting screw. Turn the ignition OFF , then disconnect the tachometer and remove the fuel pressure gauge. Install the original plug screw into the throttle body, then install the air cleaner assembly.
  10.  

REMOVAL & INSTALLATION



See Figures 3 and 4



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Fig. Fig. 3: Fuel pump/gauge sender unit installation



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Fig. Fig. 4: Fuel pump/gauge sender unit installation-with 20 gallon tank

  1. Disconnect the negative battery cable. Remove all necessary components in order to gain access to the fuel tank sending unit.
  2.  
  3. Drain the fuel from the fuel tank. Raise and support the vehicle safely.
  4.  
  5. Remove the fuel inlet and outlet hoses from the sending unit. Remove the sending unit wires.
  6.  
  7. On the 15 gallon tank, unplug the sending unit retaining lock ring by tapping it counterclockwise with a brass punch and hammer. Remove the sending unit, which incorporates the electric fuel pump, along with the O-ring seal from the fuel tank.
  8.  
  9. On the 20 gallon tank, remove the mounting bolts and lift the assembly out of the tank. Discard the gasket.
  10.  

To install:
  1. Installation is the reverse of removal. On the 20 gallon tank, be sure to use a new gasket and tighten the retaining screws to 18 inch lbs. (2 Nm).
  2.  
  3. On the 15 gallon tank, be sure to use a new O-ring seal and carefully tap the retaining lock ring clockwise with a brass punch and hammer, until the ring locks against the stops on the tank.
  4.  

 
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