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

Service

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DRAINING



  1. Remove the tank filler cap in order to release vapor pressure in the tank.
  2.  

If the pump device is equipped with a static ground wire, be sure to connect it to a metal part of the gas tank before you begin draining the fuel.

  1. Use a hand operated pump device to remove fuel through the filler neck. If difficulty is encountered, disconnect the filler hose from the tank neck and insert the pump hose directly into the tank.
  2.  
  3. The hand pump may not be able to completely drain the tank, but do your best to remove as much as possible.
  4.  
  5. On vehicles equipped with an electric fuel pump, disconnect the feed line (somewhere between the tank and engine, wherever access is convenient), then connect a length of rubber hose to the feed line. Place the other end of the rubber hose in an approved container, then operate the fuel pump to further drain the tank. On most of these vehicles, the easiest method of energizing the fuel pump is to use a 10 amp fused jumper wire to apply battery voltage to the fuel pump test connector. The connector is usually located in the engine compartment (often on the left fender).
  6.  

REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12

Except Late Model Vehicles Equipped With Shield Package
  1. Properly drain the fuel tank, then disconnect the negative battery cable.
  2.  
  3. If not done already, raise and support the rear of the truck safely using jackstands.
  4.  
  5. If equipped on late-model vehicles, loosen and remove the tank plastic shield.
  6.  
  7. Loosen the retaining clamp and disconnect the tank filler hose from the tank neck.
  8.  



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Fig. Fig. 1: Common fuel tank filler neck installation



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Fig. Fig. 2: Fuel tank mounting - vehicles without shield package

If fuel and vapor hoses or pump/sending unit wiring can be accessed at this time, they may be tagged and disconnected. If not, wait for the retaining straps to be loosened and lower the tank slightly for access.

  1. Tag and disconnect any accessible wiring or hoses from the top of the fuel tank.
  2.  
  3. Have an assistant support the fuel tank, then remove the fuel tank-to-vehicle straps and, if equipped, the isolation strips. If no assistant is available, position a floor jack to support the tank while the straps are removed.
  4.  
  5. Lower the tank slightly, then remove the sending unit or sending unit/pump wires, hoses and ground strap. Be sure to label all connections to ease installation.
  6.  
  7. Carefully lower the fuel tank from the vehicle and store in a safe place.
  8.  

To install:
  1. Raise the tank partially into position in the vehicle. If you are working without an assistant, you may wish to loosely install one of the retaining straps and use a floor jack to support the tank at an angle so there is access to the sending unit or sending unit/pump assembly (as applicable).
  2.  
  3. Connect the fuel/vapor hoses and wiring to the top of the fuel tank, as tagged during removal.
  4.  
  5. Carefully raise the fuel tank so it is fully into position and loosely secure the retaining straps. Make sure the wires and hoses are not pinched or damaged when raising the tank. Also, be sure that the isolation strips (if used) are positioned between the retaining straps and the fuel tank.
  6.  



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Fig. Fig. 3: Failure to tag the fuel lines could lead to confusion during installation



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Fig. Fig. 4: One of the retaining straps may be used to help retain the tank while connecting hoses and wires



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Fig. Fig. 5: If equipped, make sure the isolators are positioned between the straps and tank

  1. It may be easier to connect the fuel filler hose to the tank neck at this time. If desired, connect the hose and secure the clamp.
  2.  
  3. Tighten the fuel tank retaining strap fasteners to the specifications shown in the accompanying illustration.
  4.  
  5. If not done earlier, connect the tank filler hose to the tank neck and secure using the clamp.
  6.  
  7. If equipped, install and secure the tank plastic shield.
  8.  
  9. Remove the jackstands and carefully lower the rear of the truck.
  10.  



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Fig. Fig. 6: Secure the retaining straps using the fasteners



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Fig. Fig. 7: Most tanks on these vehicles are retained using 2 straps

  1. Refill the fuel tank and install the filler cap, then check for leaks.
  2.  
  3. Connect the negative battery cable.
  4.  

Late Model Vehicles Equipped With Shield Package
  1. Properly drain the fuel tank, then disconnect the negative battery cable.
  2.  
  3. Raise and support the rear of the truck safely using jackstands.
  4.  
  5. Remove the shield forward support and bracket.
  6.  



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Fig. Fig. 8: Location of fuel tank on late model vehicle equipped with shield package



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Fig. Fig. 9: Fuel tank shield - 2-door vehicles equipped with shield package

  1. While supporting the shield and tank assembly with the help of both an assistant and a floor jack, remove the remaining bolts holding the assembly to the frame, then lower it sufficiently for access to the hoses and wires.
  2.  
  3. Tag and disengage the hoses and wires from the sending unit assembly.
  4.  
  5. Carefully lower the fuel tank and shield from the vehicle; then, if necessary for service or replacement, separate the tank from the shield.
  6.  

To install:
  1. If separated, install the tank to the shield.
  2.  
  3. Carefully raise the tank and shield assembly partially into position with the help of an assistant and a floor jack.
  4.  
  5. Connect the wiring and hoses to the sending unit assembly, as tagged during removal.
  6.  
  7. Raise the tank and shield assembly fully into position, then secure to the frame using the lower retaining bolts.
  8.  



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Fig. Fig. 10: Fuel tank front shield - 4-door vehicles equipped with shield package



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Fig. Fig. 11: Fuel tank strap - 4-door vehicles equipped with shield package



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Fig. Fig. 12: Fuel tank - 4-door vehicles equipped with shield package

  1. Install the shield forward support bracket.
  2.  
  3. Remove the jackstands and carefully lower the rear of the truck.
  4.  
  5. Refill the fuel tank and install the filler cap, then check for leaks.
  6.  
  7. Connect the negative battery cable.
  8.  

SENDING UNIT REPLACEMENT



See Figures 13, 14, 15, 16 and 17

When replacing the sending unit, you will need an O-ring for the top of the fuel tank.

  1. Properly drain the fuel tank, then disconnect the negative battery cable.
  2.  

The following procedure covers sending unit replacement only. For all fuel injected vehicles, which are equipped with a sending unit/pump assembly, please refer to the electric fuel pump procedure located under TBI fuel injection, earlier in this section.



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Fig. Fig. 13: Loosen the lockring by turning counterclockwise



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Fig. Fig. 14: Once the lockring is released, the sending unit is free to be removed from the tank



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Fig. Fig. 15: Tilt the sending unit during removal in order to prevent damage to the float and pickup

  1. Remove the fuel tank assembly from the truck.
  2.  
  3. Release the sending unit lockring cam using J-24187, or an equivalent tool to turn it counterclockwise. If no tool is available, a hammer and a brass drift may be used to CAREFULLY turn the lockring and release it from the tabs. DO NOT force the ring or tank/sending unit, otherwise damage may occur.
  4.  
  5. Remove the sending unit from the top of the fuel tank. Be careful not to damage the float or pick-up while removing the unit.
  6.  
  7. Remove and discard the old sending unit-to-tank O-ring.
  8.  



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Fig. Fig. 16: ALWAYS replace the sending unit-to-tank O-ring



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Fig. Fig. 17: Common sending unit mounting

To install:
  1. Position a new O-ring on the top of the tank opening.
  2.  
  3. Carefully insert the sending unit into the tank, making sure that the unit is properly aligned so the bottom or sides of the tank do not interfere with the float or pickup. If necessary, carefully tilt the unit to insert the bottom, then straighten it out as it is inserted into the tank.
  4.  
  5. Make sure the sending unit and O-ring are properly installed, then position the lockring. Use the removal/installation tool to turn the lockring clockwise and secure the sending unit.
  6.  
  7. Install the fuel tank to the vehicle, then refill it and check for leaks.
  8.  
  9. Connect the negative battery cable and check for proper sending unit operation.
  10.  

 
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