Diagnostic Aids

Inspect for any of the conditions listed below:

• Insufficient fuel. Thoroughly inspect the fuel delivery system for sufficient fuel volume to the fuel injectors. Inspect the fuel supply components for partial blockage or restrictions.
• A stuck camshaft position actuator solenoid valve, which may cause retarded valve timing and low fuel pressure. The engine may sound like it is cranking too fast. A compression test may show low compression and exhaust flow out of the tailpipe may be noticeably less when compared to a known good vehicle. DTC P00C6 may also set. Use the scan tool to cycle the camshaft actuator solenoid valve several times and then try to start the engine. Examine the valve for contamination and clean, if necessary. Perform a dynamic test on the valve to verify correct operation, if necessary - Refer to DTC P0010, P0011, P2088, or P2089 for instructions.
• Fuel injector ON time inadequate. When this condition is present, there may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the engine control module (ECM) receives incorrect inputs from the various information sensors, the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all the engine data parameters with a scan tool and compare the values indicated with the expected values or the values from a known good vehicle.
• An unstable engine reference signal. Observe the Engine Speed parameter while cranking the engine. The scan tool should indicate a steady 200 - 300 RPM while cranking. If erratic values such as sudden spikes in the engine speed are displayed, the engine reference signal is not stable enough for the engine to start and run correctly.
• Loose, unsecured engine electrical grounds. Inspect the engine for good secure electrical grounds.
• Water or foreign material in the fuel, which can cause either a no start or a engine will not stay running condition. During freezing weather water can freeze inside the fuel system. The engine may start after 30 min in a heated repair shop. The malfunction may not recur until parked overnight in freezing temperatures. Extreme weather conditions can cause contaminated fuel to prevent the vehicle from starting.
• An ignition system that is susceptible to moisture. If the engine starts and runs after being brought into a warm, dry repair shop, the ignition system may be susceptible to moisture. Spray water on the ignition system components and wiring while cranking the engine in order to check for an engine starting or will not stay running concern.
• If the engine almost starts and then stalls, check for an open in the ground circuits of the crankshaft position sensor and the camshaft position sensor.