Diagnostic Aids
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
If the cause of an engine cranks but will not run condition has not been found, inspect for the following conditions:
- Hard starting only in cold ambient temperatures. These may cause an intermittent condition that may not occur in the service bay:
- Fuel heater inoperative, refer to Fuel Heater Inoperative .
- Ice blockage at the fuel pickup in the fuel tank. This will be a high vacuum in the supply lines while cranking, and the problem will disappear after the vehicle is brought in the service bay. It may also exhibit a start and stall condition or a starting condition with no acceleration.
- The correct cranking speed is 100 RPM cold and 180 RPM hot. A scan tool can be used to inspect cranking speed by pulling the ignition 1 relay and monitoring engine speed on the scan tool while cranking.
- Water or foreign material in fuel system
- A basic engine problem
- If the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor are disconnected or malfunctioning at the same time, an Engine Cranks But Does Not Run condition will exist.