Chevrolet Full Size Cars 1979-1989

Gasoline Fuel Filter

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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 fuel system component, always relieve pressure from the system.

FUEL PRESSURE RELEASE



Carbureted

To release the fuel pressure on the carbureted system, remove the fuel filler cap from the fuel tank in order to allow the expanded vapor to escape, then reinstall the cap. A rag should be placed around a fuel fitting before it is disconnected in order to catch any remaining fuel which may escape.

Throttle Body Injection (TBI)

When servicing TBI vehicles, the fuel tank filler cap should be removed in order to relieve tank pressure, then reinstalled. The TBI unit used on these engines contains a constant bleed feature in the pressure regulator that relieves pressure any time the engine is turned off. Therefore, no special relief procedure is required. However, a small amount of fuel may be released when the fuel line is disconnected.


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

REMOVAL & INSTALLATION



Internal Filter


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Fig. Fig. 1 If present, a new gasket should be installed with the new filter and spring



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Fig. Fig. 2 If possible, use a line wrench on the fuel line fitting



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Fig. Fig. 3 A backup wrench should be used to prevent the filter nut from loosening with the fuel line



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Fig. Fig. 4 Once the fitting is loosened, remove it from the filter nut



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Fig. Fig. 5 Loosen the filter nut using a large wrench or socket



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Fig. Fig. 6 Unthread the filter nut for access to the filter

The carburetor inlet fuel filter should be replaced every 15,000 miles, or more often if necessary.

  1. Disconnect the fuel line connection at the fuel inlet filter nut on the carburetor. A backup wrench should be used to prevent the fuel filter nut from loosening while trying to remove the line.
  2.  
  3. Carefully loosen and remove the fuel inlet filter nut from the carburetor.
  4.  
  5. Remove the filter and spring.
  6.  

To install:

If a check valve is not present with the filter, one must be installed when the filter is replaced. The check valve is necessary in order to meet Motor Vehicle Safety Standards (MVSS) for roll-over.

  1. Install the spring, filter and check valve making sure the valve end of the filter is facing the fuel line. Ribs on the fuel filter will prevent it from being installed incorrectly, unless it is forced into position.
  2.  
  3. Connect the fuel line to the filter inlet nut.
  4.  
  5. Start the engine and check for leaks.
  6.  

Inline Filter


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Fig. Fig. 7 Common inline fuel filter mounting on late model vehicles

To locate the inline filter, follow the fuel line back from the carburetor or throttle body. Inline filters are often mounted to the frame rail underneath the vehicle. It may be necessary to raise and safely support the vehicle using jackstands in order to access the filter.

  1. Disconnect the negative battery cable to prevent fuel spillage if the ignition is accidentally turned
  2.  
  3. Using a backup wrench to prevent overtorquing the lines or fittings, loosen and disconnect the fuel lines from the filter. Be sure to position a rag in order to catch any remaining fuel which may escape when the fittings are loosened.
  4.  
  5. Loosen the retaining bolt, then remove the retaining bracket and/or fuel filter from the vehicle.
  6.  

To install:

  1. Position the filter and retaining bracket with the directional arrow facing away from the fuel tank, towards to carburetor or throttle body.
  2.  

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. Install and tighten the filter/bracket retainer.
  2.  
  3. Connect the fuel lines to the filter and tighten using a backup wrench to prevent damage.
  4.  
  5. Connect the negative battery cable, then start the engine and check for leaks.
  6.  

In-Tank Filter

To service the in-tank fuel filter, please refer to the electric fuel pump removal and installation procedure in of this guide.

 
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