Diagnostic Aids

Inspect for any of the following conditions:

• Insufficient fuel can cause a no start condition. Thoroughly inspect the fuel delivery system for sufficient fuel volume to the fuel injectors. Inspect the fuel supply components for partial blockage or restrictions.
• Fuel injectors with partially blocked and restricted nozzles, or a malfunctioning solenoid, can cause a no start condition. Refer to Fuel Injector Balance Test with Special Tool  and Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F) .
• 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 fuel injectors and the injector circuit are OK, and fuel spray is detected, the fuel injector ON time may be inadequate. If the PCM 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.
• Check the crankshaft position (CKP) sensor engine reference signal with a scan tool. 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 properly.
• An intermittent condition of cranks but will not start or the engine quits while running can be caused by a PCM shutdown. There will be no fuel, spark, or data communications during a PCM shutdown. A short to ground in the 5-volt reference circuit of the engine data sensors will cause a PCM shutdown. When the short to ground is absent, the PCM will operate normally with no DTCs stored. Test for a shorted throttle position (TP) or fuel tank pressure (FTP) sensor, or shorted sensor wiring.
• Inspect the engine electrical grounds G104 and G105, if the engine has no spark and no fuel injector pulse with no DTCs. Refer to Power Distribution Schematics and Ground Distribution Schematics in Wiring Systems.
• If the engine almost starts and then stalls, check for an open in the ground circuits of the CKP sensor and the camshaft position (CMP) sensor.
• Water or foreign material in the fuel can cause a no start or engine will not stay running condition. During freezing weather water can freeze inside the fuel system. The engine may start after 30 minutes 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.
• A vehicle that starts and runs after being brought to the repair shop for a no start complaint, may have an ignition system that is susceptible to moisture. Spray water on the ignition system components and the wiring in order to check for an engine starting or will not stay running concern.

An intermittent malfunction may be caused by fault in any of the critical information or component electrical circuits. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .

Repair any electrical circuit faults that were found. Refer to Wiring Repairs in Wiring Systems.