GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Electric Fuel Pump

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The electric pump is attached to the fuel sending unit, located in the fuel tank.

TESTING



See Figures 1 through 5

  1. Properly relieve the fuel system pressure.
  2.  
  3. Leave the gauge attached to the pressure fitting on the fuel inlet pipe.
  4.  
  5. If disconnected during the fuel pressure relief procedure, reconnect the negative battery terminal.
  6.  
  7. Disconnect the vacuum hose from the regulator.
  8.  



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Fig. Fig. 1: Fuel pump relay circuit



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Fig. Fig. 2: MFI fuel delivery circuit



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Fig. Fig. 3: MFI fuel pump and relay diagnostic chart



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Fig. Fig. 4: MFI fuel pump and relay diagnostic chart



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Fig. Fig. 5: MFI fuel pump and relay diagnostic chart

  1. Turn the ignition ON and listen for the pump to run (is should run for 2 seconds). If necessary, cycle the ignition OFF for 10 seconds and then ON again in order to build maximum system pressure. Check that pressure is at specification:
    1. Note the pressure after the pump stops, it should be 35-38 psi (245-256 kPa) and should hold steady. If not, refer to the accompanying fuel system diagnostic charts.
    2.  

  2.  

REMOVAL & INSTALLATION



Removal and installation of the fuel pump and sending unit assembly is the same on MFI vehicles as it is for TBI vehicles. Please refer to the TBI procedures earlier in this section for electric fuel pump replacement.

 
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