Diagnostic Aids

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The fuel return volumes vary based on the American Petroleum Institute (API) rating of the diesel fuel.
A fuel injector may have high fuel return flow only at higher engine temperatures.