GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Diesel Fuel Filter

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REMOVAL & INSTALLATION



See Figures 1 and 2

The diesel fuel filter is mounted on the rear of the intake manifold, and is larger than that on a gasoline engine because diesel fuel is generally dirtier (has more suspended particles than gasoline).



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Fig. Fig. 1: Exploded view of the diesel fuel filter element and related components



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Fig. Fig. 2: Common diesel fuel filter assembly

Filter Element
  1. Disconnect the negative battery terminal.
  2.  
  3. Disengage the water sensor wire connector from the filter assembly.
  4.  
  5. Disconnect the water sensor-to-main body hose.
  6.  
  7. Using a filter band wrench, remove the fuel filter element by turning the cartridge counterclockwise, while being careful not to spill diesel fuel from the element.
  8.  
  9. Drain the fuel from the element into a container and discard it. Take precautions to avoid the risk of fire during replacement procedures.
  10.  
  11. Remove the water and heater sensor from the bottom of the used filter element.
  12.  

To install:
  1. Apply a thin coat of diesel fuel to the water sensor O-ring, then install the water and heater sensor on the bottom of the replacement filter element and tighten.
  2.  
  3. Wipe all filter sealing surfaces clean before installing the new filter and apply a thin coat of diesel fuel to the gasket on the new fuel filter element.
  4.  
  5. Install the new filter element by turning it clockwise until the gasket contacts the sealing surfaces on the main filter body. Hand tighten another 2 / 3 of a turn after the gasket contacts the sealing surface; DO NOT overtighten.
  6.  
  7. Re-engage the water sensor wiring connector, then disconnect the fuel outlet hose from the injection pump and place the end in a clean container.
  8.  
  9. Operate the priming pump handle on the injection pump several times to fill the new filter with fuel, continue until fuel flows from the outlet hose. Reconnect the outlet hose to the injection pump when priming is complete.
  10.  

It is very important to prime the new filter element before starting the engine, as the shock of the diesel engine's high operating fuel pressure hitting a dry element can tear small pieces of debris away and allow them to pass into the injection pump and injectors, possibly causing injection pump or injector damage.

  1. Start the engine and check for leaks.
  2.  

Filter Assembly
  1. Disconnect the negative battery terminal.
  2.  
  3. Disengage the water sensor electrical connector.
  4.  
  5. Disconnect the fuel hoses from the filter assembly.
  6.  
  7. Remove the filter assembly-to-bracket screws, the filter main body, element and sensors as an assembly.
  8.  
  9. To install, reverse the removal procedures. Please refer to the draining the water separator procedure located later in this section, in order to properly prime the fuel system.
  10.  

Draining the Water Separator
  1. Turn the engine OFF and allow it to cool.
  2.  
  3. Open the hood and place a 2 quart container under the end of the drain hose attached to the separator.
  4.  
  5. Turn the wing nut about four turns counterclockwise to open the drain plug, then operate the priming pump lever until all of the water is drained and ONLY clean diesel fuel flows from the water separator.
  6.  
  7. Tighten the drain plug wing nut clockwise until securely closed; DO NOT overtighten. Again, operate the priming pump handle until resistance is felt, indicating that the fuel filter is properly primed.
  8.  
  9. Start the engine and check for fuel leaks from the separator and fuel lines. Make sure the WATER IN FUEL light is OFF; if the light remains ON, the fuel tank must be purged of water with a siphon hose and hand pump fed into the tank through the fuel filter.
  10.  


CAUTION
DO NOT attempt to siphon any fuel tank contents by using mouth suction to start the siphon effect. Diesel fuel is poisonous and is by far the worst tasting stuff you can imagine. Use a hand siphon pump or power drill attachment to pull the water from the fuel tank.

 
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