The first step is to relieve fuel pressure and disconnect the battery's negative terminal before performing various maintenance actions on the throttle body assembly. If you are working on a fuel injector, ensure that its electrical connector is removed, the injector retainer screw is taken off, and it is pried out gently to access upper and lower O-rings that are replaced upon removal. Also check the fuel injector filter and clean out dirt in fuel lines and tank. When installing a new O-ring, lightly lubricate it with transmission fluid and make sure it is positioned correctly. In terms of direction, push the injector assembly straight into the fuel injector cavity, aligning the electrical connector end. Fasten it down using a threaded locking compound applied to the retainer screw. Thereafter, reinstall the air cleaner housing assembly, adapter, and gaskets while checking for fuel leaks with engine off and ignition on. Regarding the steps involved in removing a fuel pressure regulator, remove four attaching screws holding down a pressure regulator cover assembly while keeping regulator compressed; replace a pressure regulator diaphragm assembly when necessary. Install the new diaphragm first followed by the spring seat then spring ensuring proper seating of diaphragm so that it doesn't get twisted or wrinkled while being installed or used henceforth. Replace diaphragm over mounting holes before fixing with four screw assemblies coated with thread locking compound. The negative battery cable should be reconnected and check for any other fuel leaks before you shut off engine/ignite on again. In order to keep Throttle Position Sensor (TPS) functional unplug its electrical connector; remove two attaching screws; close throttle valve; position TPS on throttle shaft before refitting; rotate counter-clockwise until mount holes are aligned then secure with two attaching screws. As soon as this process ends put back air cleaner housing assembly, adapter plus gaskets connecting cable at negative battery terminal again.In case of an Idle Air Control (IAC) valve, unplug wiring connection going straight to the IAC valve and then remove the IAC valve mounting screws before taking out IAC. Replace O-ring, clean seating surfaces of the IAC valve. If it is fully extended, measurement should be taken between the valve pintle tip and flange mounting surface; if this exceeds the set specifications bring it down to avoid damaging the part. As you retract IAC valve into its bore in throttle body apply a little transmission fluid on new O-ring for lubrication purpose and to prevent it from getting cut during this process. Fasten IAC valve securely with thread locking compound on attaching screws plus connect electrical connector. Finally re-install air cleaner housing assembly, adapter and gaskets while reconnecting battery cable. Start engine and let it warm up sufficiently until PCM will establish correct idle speed.For Tube Module Assembly, remove tube module assembly attaching screws; discard old gasket as well as any remaining material of gasket at throttle body. Install a new tube module gasket and the tube module itself after cleaning both areas thoroughly.Reinstall air cleaner housing assembly, adapter and gaskets.The Fuel Meter Assembly can be maintained by removing fuel meter assembly from throttle body injection unit, two fuel meter body attaching screws and washers.If a new fuel meter is being installed transfer fuel pressure regulator and fuel outlet nut to it from old meter.Discard old fuel meter body-to-throttle body gasket as new one is put in its place.Make sure that you get the correct cutouts matching each other in order to install fuel meter onto throttle body tightening screw adequately.Upon removal of Throttle Body Assembly, unplug electrical connectors from fuel injector, IAC, TPS.Remove old throttle body-to-intake manifold gasket with throttle body mounting studs.Install new one on tube module assembly.IAC valve as well as TPS should also be mounted on throttle body assembly.Install a new fuel meter body-to-throttle body gasket aligning cutouts with openings.Insert fuel injector and the fuel meter assembly at this stage.Finally, install throttle body assembly on intake manifold using new throttle body-to-intake manifold gasket and tighten mounting studs to specified torque values.Minimum idle speed adjustment requires you to ground the diagnostic terminal of the ALDL connector, turn on the ignition, wait 30 seconds, unplug the IAC valve electrical connector, start the engine and adjust a particular idle stop screw with transmission in Neutral (manual) or Park (automatic) to achieve certain RPM. After that reattach IAC valve electrical connector again; remove any vacuum line ports that might still be present and reinstall air cleaner housing assembly, adapter plus gaskets. For non-adjustable TPS output check, using a digital voltmeter connect it from center terminal "8" to outside terminal "A" of TPS connector.With engine off but ignition on TPS voltage should not exceed 1.25 volts in such case. If this exceeds specifications replace TPS.
Posted by GMPartsGiant Specialist 
