Chevrolet Citation/Omega/Phoenix/Skylark 1980-1985 Repair Guide

Throttle Body

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GENERAL INFORMATION





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Fig. Fig. 1 Throttle body vacuum port locations

The TBI system, used on 1982-85 four cylinder engines, is a complete electronic system which meters and delivers precise amounts of fuel and air to the engine, according to the exact engine operating requirements at any given time. The system is controlled by the same on-board computer (ECM) used with the emissions system (CCC). Through the monitoring of various sensors, the ECM determines the optimum air/fuel ratio and signals the TBI unit to adjust the ratio accordingly. TBI is designed to offer the owner trouble-free starting, immediate throttle response, and maximum fuel efficiency; regardless of weather conditions, engine rpm, temperature or load.

Trouble diagnosis of the injection system is nearly impossible for the novice mechanic to perform, because of the interaction between the injection, emissions, and ignition systems, all of which are controlled by the ECM. Should you encounter any type of engine performance problem, have a complete CCC system test performed by a qualified, professional technician.

REMOVAL & INSTALLATION





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Fig. Fig. 2 Unplug the electrical connector from the Idle Air Control (IAC) valve (see arrows)



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Fig. Fig. 3 Detach the electrical connector from the fuel injector



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Fig. Fig. 4 Unfasten the throttle linkage retaining clip



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Fig. Fig. 5 Disconnect the vacuum lines from the throttle body



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Fig. Fig. 6 When loosening the fuel lines, use a backup wrench to prevent the lines from bending



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Fig. Fig. 7 Remove the fuel supply and return lines from the throttle body



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Fig. Fig. 8 Unfasten the throttle body mounting bolts ...



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Fig. Fig. 9 ... then lift the throttle body up and off the intake manifold



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Fig. Fig. 10 Remove the throttle body plenum gasket

Before attempting TBI removal relieve the fuel pressure, as outlined earlier in this section.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Disconnect the harness electrical connectors to the idle air control valve, throttle position sensor and injector.
  6.  
  7. Disconnect the throttle linkage, return spring, and cruise control linkage, if so equipped.
  8.  
  9. Disconnect the vacuum hose from the throttle body. Note the hose routing for installation.
  10.  
  11. Disconnect the fuel supply and return lines at the throttle body. (See note above.)
  12.  
  13. Remove the three throttle body retaining bolts and remove the throttle body.
  14.  
  15. Installation is the reverse of removal. Torque the throttle body retaining bolts to 120-168 inch lbs.
  16.  

 
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