Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT:

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
A fuel injector leak into the combustion chamber may result in mechanical damage to the cylinder. If any fuel spray comes out of a glow plug hole during the compression test, replace the fuel injector of the affected cylinder.
If fuel vapor is emitted during the engine compression test, replace the affected fuel injector and inspect for fuel contamination. refer to Contaminants-in-Fuel Diagnosis .

Perform the engine compression test. Refer to Engine Compression Test .

If the compression indicated any of the cylinders had low compression, refer to Symptoms - Engine Mechanical .

IMPORTANT:

Failure to correctly identify the cylinder positions may result in the replacement of the wrong injector.
During replacement of the injectors, inspect the inlet and outlet fittings for corrosion or contamination. Refer to Contaminants-in-Fuel Diagnosis .

If the engine did not have low compression on any of the cylinders, replace the fuel injectors on the cylinders that had low cylinder power contribution, high balance rates, or a noise/smoke change during cancellation.