GM Astro/Safari 1985-1996 Repair Guide

Mechanical Fuel Pump

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The mechanical fuel pump is located on the right front of the engine.

REMOVAL & INSTALLATION




CAUTION
Before removing any component of the fuel system, be sure to reduce the fuel pressure in the system. Keep a fire extinguisher close by when servicing the fuel system. Place a rag under the fuel line and slowly remove the line from the fitting.

  1. Disconnect the negative battery cable, the fuel inlet hose from the fuel pump and the vapor return hose (if equipped).
  2.  
  3. Disconnect the fuel outlet hose from the fuel pump.
  4.  
  5. Remove the fuel pump-to-engine bolts, the fuel pump, the pushrod, the gasket and the mounting plate.
  6.  
  7. Using a putty knife, clean the gasket mounting surfaces.
  8.  

To install:
  1. Use a new gasket with silicone sealer.
  2.  
  3. Install the mounting plate, gasket, pushrod and fuel pump. Torque the mounting bolts to 27 ft. lbs. (37 Nm).
  4.  
  5. Connect the fuel outlet hose to the fuel pump.
  6.  
  7. Connect the fuel inlet hose to the fuel pump and the vapor return hose (if equipped).
  8.  
  9. Connect the negative battery cable, start the engine and check for fuel leaks.
  10.  

TESTING



Flow Test
  1. Remove the fuel pump-to-carburetor line from the carburetor.
  2.  
  3. Place the fuel line into a clean container.
  4.  
  5. Crank the engine; approximately 1 / 2 pint of the fuel should be delivered in 15 seconds.
  6.  
  7. If the fuel flow is below minimum, inspect the fuel system for restrictions; if no restrictions are found, replace the fuel pump.
  8.  

Pressure Test

The following procedure requires the use of a GM Fuel Pressure Gauge tool No. J-29658-A or equivalent.

  1. Remove the air cleaner, then disconnect and plug the THERMAC vacuum port on the carburetor.
  2.  
  3. Place a rag (to catch excess fuel) under the fuel line-to-carburetor connection. Disconnect the fuel line from the carburetor.
  4.  

When disconnecting the fuel line, use a back-up wrench to hold the fuel nut on the carburetor.

  1. Using a GM Fuel Pressure Gauge tool No. J-29658-A or equivalent, install it into the fuel line.
  2.  
  3. Start the engine and observe the fuel pressure. The pressure should be 4-6.5 psi (27.5-44.9 kPa).
  4.  

If the fuel pressure does not meet specifications, inspect the fuel system for restrictions or replace the fuel pump.

  1. Stop the engine, relieve the fuel pressure and remove the GM Fuel Pressure Gauge tool No. J-29658-A or equivalent.
  2.  
  3. Install a new fuel line-to-carburetor O-ring or washer. Unplug the THERMAC vacuum port. Start the engine and check for fuel leaks.
  4.  

 
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