How to Clean Chevy Throttle Body Injectorsby Lee Sallings
The throttle body injection system used by Chevy was a natural progression from the carburetor previously used. Pressurized fuel is strained through screen-type filters before it is introduced into the engine through a pair of injectors located above the throttle body's venturi and throttle plate. Over time, varnish and sediment clog the screens and injectors, causing inefficient fuel atomization. Many times cleaning the injectors will restore proper atomization and engine performance.
Remove the air cleaner by removing the wing nut, lid, vacuum lines and air ducts attached to it, then lifting it out of the engine compartment. Set the air cleaner aside, with the wing nut, to avoid losing the wing nut.
Start the engine and allow it to warm up for a few minutes. The injector cleaner used in the process is not as combustible as gasoline so a warm engine is critical to prevent spark plug fouling. Remove the fuel pump fuse and allow the engine to stall from lack of fuel. This relieves the fuel pressure on the system. Block the fuel return line leading from the injectors to the fuel tank. It is the larger of the two fuel lines attached to the back side of the throttle body. Remove it from the throttle body and plug the fitting in the throttle body with an adapter from the kit
Locate the fuel lines attached to the back of the throttle body. The smaller of the two lines is the fuel inlet line. Find the fuel service port: it will be located a few inches away from the throttle body on the inlet line. Screw the gauge assembly from the cleaning kit onto the service port. Wipe up any gasoline spilled on the engine, when attaching the hose to the fitting, to prevent fire. Screw a can of pressurized injector cleaner to the gauge assembly can tap and open the can by turning the thumbscrew all the way into the can then all the way out.
Adjust the regulator on the gauge assembly to 35 psi and start the warmed engine. The pressurized can of cleaner will force the cleaner into the injector assembly, softening the deposits clogging the injectors. Allow the engine to run on the cleaner until the can is emptied.
Remove the cleaner gauge assembly, remove the plug from the fuel return fitting then reinstall the return fuel line. Replace the fuel pump fuse. Hold the throttle pedal to the floor and start the engine. This may take a few attempts for the fuel pump to reprime the system and restore the fuel pressure. Check for fuel leaks at the lines, then re-install the air cleaner and test-drive.
Items you will need
- Fuel injector cleaning kit
- Pressurized fuel injector cleaner
- Service manual
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