The 1999 Chevy S-10 pickup truck with a 4.3-liter model 220 engine uses a throttle body injection system, or TBI. In this type of system the throttle body is positioned on the top center of the intake manifold and has two separate bores, each containing one fuel injector at the topside of the bore. The throttle plates are below the injectors. With the air cleaner removed, the injector spray pattern can be observed and irregularities easily diagnosed. The Vortec engine, which comes in some models, uses a different style system.
Instructions
- 1
Loosen the fuel cap to relieve the fuel pressure. This type of system sustains fuel pressure in the fuel tank only when the key is off.
2Open the hood and set the prop. Disconnect the negative battery cable using a wrench. Remove the two air cleaner wing nuts and lift off the assembly.
3Disconnect both fuel injectors by squeezing the tabs on both sides of each connector and lifting it off. Remove the screws in the fuel meter cover surrounding the injectors, using a Phillips screwdriver. Lift the fuel meter cover off but leave the gasket in place.
4Remove the injectors by laying a metal dowel horizontally on the throttle body behind the injectors. Use the dowel as a fulcrum by placing the flat-head screwdriver on the dowel and the blade of the screwdriver under the top flange of the injector. Push down on the screwdriver to carefully pry the injector out of its housing.
5Discard the cover gasket. Remove the large O-ring in the top of the injector cavity in the throttle body and the small O-ring on the nozzle end of the injector. Discard them both.
6Check the fuel filter on the base of the injector, if so equipped, and if in need of cleaning or replacing, rock the filter side to side to remove it. Install the fuel filter large opening up, with a twisting motion.
7Install the small O-ring on the base of the injector tip. Install the backup spacer in the meter cavity if one was present. Install the large O-ring in the top of the throttle body opening above the backup washer, making sure the two are flush with the top of the throttle body cavity.
8Place a little transmission fluid on the small O ring on the injector. Insert the injector into its cavity in the throttle body by first aligning the raised lug on the injector with the slot in the throttle body. Push the injector down firmly until it seats. The injector is seated properly if the electrical terminals are parallel to the throttle plate rod.
9Install the new meter cover gasket. Install the meter cover over the gasket. Spread a small amount of thread sealer compound on the screw threads and install the screws. Torque the screws to 30 inch-pounds. Install the electrical plugs on both injectors. Connect the negative battery cable and tighten it with a wrench. Install the fuel cap loosened earlier.
10Start the truck and check for leaks around the injectors. Shut the engine off. Install the air cleaner assembly and lower the hood.
