Pontiac Fiero 1984-1988 Repair Guide

Throttle Body Unit

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REMOVAL & INSTALLATION




CAUTION
To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure before servicing any fuel system component. If this procedure is not performed, fuel may be sprayed out of the connection under pressure. Always keep a dry chemical (Class B) fire extinguisher near the work area.

  1. Relieve the fuel pressure.
  2.  
  3. Remove the thermac hose from the engine fitting and air cleaner.
  4.  
  5. Disconnect the electrical connectors to the Idle Air Control (IAC), Throttle Position Sensor (TPS) and injector.
  6.  
  7. Remove the throttle linkage, return spring and cruise control linkage if so equipped.
  8.  
  9. Disconnect the vacuum hoses from the throttle body. (Mark the hose routing for proper connection during installation.
  10.  
  11. Disconnect the fuel supply and return steel lines from the throttle body using a flare nut and backup wrench.
  12.  
  13. Remove the three bolts securing the throttle body-to-engine. Remove the throttle body assembly from the engine.
  14.  

To install:

  1. Clean the throttle body and intake manifold sealing surfaces with solvent and a gasket scraper.
  2.  
  3. Install the throttle body with a new gasket onto the manifold and torque the two or three bolts to 13 ft. lbs. (17 Nm).
  4.  
  5. Inspect the O-ring seals for the inlet and return lines and replace if damaged. Install the fuel lines using a flare nut and backup wrench. Torque the lines to 17 ft. lbs. (23 Nm).
  6.  
  7. Install the throttle return spring, throttle linkage and cruise control linkage if so equipped.
  8.  
  9. Reconnect the electrical connectors to the throttle position sensor, idle air control motor and injector.
  10.  
  11. Install the air cleaner, start the engine and check for fuel leaks.
  12.  

OVERHAUL





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Fig. Fig. 1 Exploded view of the model 300 throttle body assembly-1984-86 2.5L engine



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Fig. Fig. 2 Exploded view of the model 700 throttle body assembly-1987-88 2.5L engine

The procedures that follow apply to complete disassembly, cleaning and reassembly of the TBI assembly removed from the engine. In many cases, service repair of individual components may be completed without removing the entire unit from the engine. Refer to the "Model 300 and 700 Throttle Body Injection" parts breakdown illustrations in this section for disassembly and reassembly.

  1. Release the fuel pressure and remove the throttle body assembly. Refer to the "Throttle Body Unit" removal procedures in this section.
  2.  
  3. Remove the five fuel meter cover screws and lockwashers while holding the cover on the fuel meter body.
  4.  
  5. Lift the fuel meter cover including the fuel pressure regulator assembly off the throttle body.
  6.  
  7. Discard the fuel outlet passage gasket only. Leave the fuel meter cover gasket on the fuel meter body.
  8.  


CAUTION
Do not remove the four screws securing the fuel pressure regulator assembly to the fuel meter cover. The regulator cover contains a large spring under heavy tension which, if accidentally released, could cause personal injury. The assembly is serviced as a complete unit. Do not immerse the fuel meter cover in any type of industrial cleaner because damage to the pressure regulator may result.

  1. Remove the sealing ring for the base of the fuel pressure regulator.
  2.  
  3. Clean the parts with carburetor cleaner or equivalent.
  4.  

ASSEMBLY



  1. Install a new dust seal for the fuel pressure regulator into the recess on the fuel meter body.
  2.  
  3. Install a new fuel return passage gasket on the fuel meter cover.
  4.  
  5. Install a new fuel meter gasket on the fuel meter body.
  6.  
  7. Install the fuel meter cover making sure the pressure regulator dust seal and cover gaskets are in place. Apply thread locking compound to the threads of the five fuel meter cover attaching screws. The two short screws go next to the fuel injector. Torque the five cover attaching screws to 28 inch.lb. (3.0 Nm).
  8.  
  9. Install the throttle body assembly as outlined in the "Throttle Body Unit" installation.
  10.  

 
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