GM Full-Size Trucks 1970-1979 Repair Guide

Fuel Filter

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CAUTION
To reduce the chance of personal injury, cover the fuel line with cloth to collect the fuel and then place the cloth in an approved container.

There are three types of fuel filters; internal (in the carburetor fitting), inline (in the fuel line) and in-tank (the sock on the fuel pickup tube).


CAUTION
Before removing any component of the fuel system, the fuel system pressure must be relieved. Please refer to the fuel pressure relief procedures, located in Fuel System in this repair guide.

REMOVAL & INSTALLATION



Internal Filter

Internal filters are located in the inlet filling on all carburetors. Elements are placed in the inlet hole with the gasket surface outward. A spring holds the element outward, sealing it by compressing a gasket surface against the inlet fitting. A check valve is also built into the filter element.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect fuel line connection at fuel inlet filter nut.
  4.  
  5. Remove fuel inlet filter nut from carburetor.
  6.  
  7. Remove filter and spring.
  8.  

To install:
  1. If removed, install check valve in fuel inlet filter. The fuel inlet check valve must be installed in the filter to meet Motor Vehicle Safety Standards (M.V.S.S.) for roll-over. New service replacement filter must include the check valve.
  2.  
  3. Install the fuel inlet filter spring, filter, and check valve assembly in the carburetor. The check valve end of filter faces toward fuel line. The ribs on the closed end of the filter element prevent the filter from being installed incorrectly unless forced.
  4.  
  5. Install the nut in the carburetor and tighten it to 18 ft. lbs. (24 Nm).
  6.  
  7. Attach the fuel line, then tighten the connection securely.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Start engine and check for leaks.
  12.  

Inline Filter

The inline filter on the fuel injected models is found along the frame rail.

  1. Disconnect the negative battery cable.
  2.  
  3. Properly relieve the fuel system pressure, as outlined in Fuel System of this guide.
  4.  
  5. Using a back-up wrench, disconnect the fuel lines.
  6.  
  7. Remove the fuel filter from the retainer or mounting bolt.
  8.  

To install:

The filter has an arrow (fuel flow direction) on the side of the case, be sure to install it correctly in the system, the with arrow facing away from the fuel tank.

  1. To install, reverse the removal procedures.
  2.  
  3. Connect the negative battery cable.
  4.  
  5. Start the engine and check for leaks.
  6.  

 
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