Engine Cranks But Does Not Run

Engine Cranks but Does Not Run

Description
The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine to not start. The diagnostic table directs the service technician to the appropriate system diagnosis. The diagnostic table assumes the following conditions are met:
- The battery is completely charged and terminals are cleaned and tight.
- The engine cranking speed is normal.
- There is adequate fuel in the fuel tank.
- There is no air in the fuel line.
- Filters (Air, Fuel) are clean.
- Fuses and slow blow fuses are normal.

NOTE: The engine will start even if exhaust brake is fully engaged.

Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- Poor connections
- Misrouted harness
- Rubbed through wire insulation
- Broken wire inside the insulation

Check for the following conditions:
- Poor connection at engine control module (ECM): Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

NOTE: The Actual Fuel Rail Pressure on scan tool will only update with the engine running or one time after the key is cycled when the ignition has been turned OFF for longer than 10 seconds.

Test Description
The numbers below refers to the step number on the diagnostic table.
5. If the fuel rail pressure (FRP) regulator low control circuits between the ECM and the FRP regulator are shorted to ground, "Actual FRP Regulator" will be approximately 500 mA lower as compared with "Desired FRP Regulator".

Engine Cranks but Does Not Run
Schematic Reference: Engine Controls
Schematics Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views

Step 1 - 3:

Step 4 - 8:

Step 9 - 13: