Engine Cranks But Does Not Run

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.
- The cranking speed is within specifications. Refer to Engine Cranks Slowly in Starting and Charging. Engine Cranks Slowly
- 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. These may cause an intermittent condition that may not occur in the service bay:
- Fuel heater inoperative-Refer to Fuel Heater Inoperative. 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.
- Water or foreign material in fuel system
- A basic engine problem
- More than 1 ohm of resistance in the ignition 1 voltage circuit to the fuel injection control module may cause a crank no start condition.
- Low engine coolant may cause the engine to shut down.

TEST DESCRIPTION

Steps 1-12:

Steps 13-21:

Steps 22-27:

The numbers below refer to the step numbers on the diagnostic table.
5. This step tests for an ignition 1 voltage supply to the engine control module (ECM).
6. If there is fuel in the engine oil, fuel may be leaking from the fuel injector or fuel injection pump into the crankcase.
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.
9. In some cases, no compression, possibly with excessive fuel, in a single cylinder can cause a no start.
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).