Engine Cranks But Does Not Run

CIRCUIT DESCRIPTION
The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis.

The Engine Cranks But Does Not Run diagnostic table assumes the following:
^ The batteries are completely charged. Refer to Battery Inspection/Test in Starting and Charging.
^ The cranking speed is within specifications. Refer to Engine Cranks Slowly in Starting and Charging.
^ There is adequate fuel in the fuel tanks.

DIAGNOSTIC AIDS
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.
^ 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.

TEST DESCRIPTION

Engine Cranks but Does Not Run - Steps 1-4:

Engine Cranks but Does Not Run - Steps 5-15:

Engine Cranks but Does Not Run - Steps 16-27:

The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for an ignition 1 voltage supply to the engine control module (ECM).
5. This step tests the 12-volt reference circuit to the CKP sensor and the CMP sensor. The 12-volt reference circuit for the CKP sensor and the CMP sensor is connected internally within the ECM. If the 12-volt reference circuit is shorted to ground, the engine will not start and no engine speed will be indicated on the scan tool.
7. If the fuel system will not even briefly prime to 10 psi and will not start, the check valve in the fuel filter/heater element housing is stuck open.
8. This step determines if the fuel system is bleeding down causing a no start. The fuel pressure will slowly drop to 0 psi, but should still be above 8 psi 10 seconds after pressurizing the fuel system.
10. This step determines if the problem is a stuck open or broken fuel injector. If fuel vapors come out of any of the glow plug holes, excessive fuel is being sent into a cylinder, and not being distributed to all of the fuel injectors.
11. The engine will not run without an actual fuel rail pressure more than 10 MPa (1,450 psi).
13. If the no-start condition takes place in cold operating temperatures, 2-4°C (35-40°F) or colder, a glow plug system failure may cause the no-start condition.
15. In some cases, no compression, possibly with excessive fuel, in a single cylinder can cause a no start.