GM Astro/Safari 1985-1996 Repair Guide

Fuel Filter

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There are 3 types of fuel filters used: The internal (1985 4.3L carbureted models), the inline (TBI, CMFI and CSFI) and the in-tank.


CAUTION
Before removing any component of the fuel system on fuel injected models, be sure to properly release the system pressure. For details on fuel system pressure release procedures and related safety precautions, please refer to Fuel System of this guide.

The internal carburetor filter and the inline fuel filter should be replaced at least every 30,000 miles (48,000 km) to help assure a clean and trouble-free fuel delivery system. The intank filter should not require replacement unless it becomes clogged. If a vehicle is purchased used and the last fuel filter service is not documented, it is probably a good idea to replace the internal or inline filter anyway to be sure of its condition.

REMOVAL & INSTALLATION



Internal (Carbureted Models)

See Figure 1



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Fig. Fig. 1: Exploded view of the internal fuel filter-carbureted engines

  1. Disconnect the negative battery cable for safety.
  2.  
  3. At the carburetor, disconnect the fuel line connection from the fuel inlet filter nut.
  4.  
  5. Remove the fuel inlet filter nut from the carburetor.
  6.  
  7. Remove the filter and the spring, then discard the old filter.
  8.  

To install:

A check valve MUST be installed in the filter to meet the Motor Vehicle Safety Standards for roll-over. When installing a new filter, pay attention to the direction the fuel must flow through it; it MUST be installed with the check valve end facing the fuel line. The new filter is equipped with ribs on the closed end to ensure that it will not be installed incorrectly unless it is forced.

  1. Install the spring and the new filter/check valve assembly into the carburetor inlet, followed by the fuel inlet nut.
  2.  
  3. Tighten the fuel inlet nut to 18 ft. lbs. (25 Nm).
  4.  
  5. Install the fuel line and tighten the connection.
  6.  
  7. Connect the negative battery cable, then start the engine and check for leaks.
  8.  

Inline

See Figures 2, 3, 4, 5, 6 and 7



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Fig. Fig. 2: Exploded view of the late-model 2.5L engine fuel filter mounting



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Fig. Fig. 3: Most vehicles covered by this guide use a fuel filter which is mounted vertically along the frame rail



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Fig. Fig. 4: A backup wrench is used to keep the filter from twisting (damaging the other fuel line if still attached)



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Fig. Fig. 5: Before loosening the fitting completely, position a rag to catch any remaining fuel which may spill



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Fig. Fig. 6: The fuel filter on some late-model vehicles is mounted horizontally along the frame rail



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Fig. Fig. 7: Once the filter and clamp assembly is removed (on late-model vehicles) the filter should be separated and discarded (but retain the clamp for the new filter)

The location of the inline fuel filter varies depending upon the year and model of the vehicle. On most models, the filter can be found along one of the vehicle's frame rails (usually the left side, towards the front of the vehicle). But, on some later versions of the 2.5L engine, the filter may be found under the engine cover, at the rear of the engine. To save you the trouble of removing the engine cover, we recommend that no matter which engine your van uses, that you check along the frame rails first. If necessary, follow the fuel lines from the tank at the rear of the vehicle, forward until you either find the filter, or the line disappear into the engine cavity.

  1. Properly relieve the fuel system pressure, then disconnect the negative battery cable.
  2.  

When relieving the fuel system pressure, remember to loosen the fuel tank filler cap. If the tank pressure is not released, fuel could be forced through the lines and out the opening, as soon as the fuel fittings are loosened.

  1. Locate the filter along the frame rail or under the engine cover. As necessary for access, either raise and support the vehicle using jackstands or remove the engine cover.
  2.  
  3. Using 2 wrenches (one for backup on the filter itself to keep it from spinning), loosen and remove the fuel lines from the filter. On models where the filter is mounted vertically along the frame rail, it may be easier to loosen the upper fitting first, then the lower fitting.
  4.  

Fittings which are stuck to the filter with corrosion may be very difficult to loosen. ALWAYS use the proper size wrench (a line wrench is preferable to a standard open-end tool) or you will risk rounding off the fuel line fittings. Also, spraying the fitting with penetrating oil prior to loosening may help to loosen the corrosion and free the fitting.

  1. Note the direction which the filter is mounted for installation purposes (there may still be a visible arrow on the side of the old filter, or the filter ends may be different). Loosen the filter or filter clamp-to-bracket bolt (as applicable), then remove the filter and discard it. If the filter and clamp come of the bracket as an assembly, retain the clamp for installation on the new filter.
  2.  

To install:

When installing a new filter, be sure to install it facing the proper direction. Normally an arrow is found on the side of the filter housing to show proper direction of flow (toward the engine). If no arrow is present, position it in the same way as you noted during removal of the old filter.

  1. If the clamp was removed with the old filter, position it over the replacement.
  2.  
  3. Install the new filter into the bracket and thread, but do not tighten, the retaining bolt.
  4.  

If O-rings are used on the threaded fittings, they should be replaced to assure a proper seal.

  1. Connect the fuel lines and tighten using a backup wrench to keep the filter from spinning.
  2.  
  3. Tighten the fuel filter retaining bolt.
  4.  
  5. Connect the negative battery cable, then pressurize the fuel system (by cycling the ignition or cranking the engine) and check for leaks.
  6.  
  7. Either remove the jackstands and carefully lower the vehicle, or install the engine cover, as applicable.
  8.  

Intank

See Figure 8



Click image to see an enlarged view

Fig. Fig. 8: The intank fuel filter (strainer) is attached to the bottom of the pump or sending unit assembly-TBI model shown

The intank filter (also know as the strainer) is usually constructed of woven plastic and is located on the lower end of the fuel pickup tube in the fuel tank. The filter prevents dirt and discourages water from entering the fuel system; though water will enter the system if the filter becomes completely submerged in the water. The filter is normally self cleaning and requires no periodic maintenance; should this filter become clogged, the fuel tank must be flushed.

  1. Remove the fuel pump or sending unit from the vehicle, as applicable. For details, please refer to Fuel System of this guide.
  2.  
  3. Carefully remove the fuel filter (strainer) from the fuel pump and clean or replace it, as necessary.
  4.  

When installing the intank fuel filter, be careful not to fold or twist it for this may restrict the flow.

  1. Install the strainer, then install the fuel pump or sending unit.
  2.  

 
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