Engine Cranks, But Will Not Run

This article has been updated with bulletin No.: 71-65-29.

ENGINE CRANKS BUT DOES NOT RUN

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Engine Control (Ignition Control (IC) Module):

CIRCUIT DESCRIPTION
The ignition system uses a waste spark method of spark distribution. During cranking, the Ignition Control (IC) module monitors the crankshaft position sensor signals. The signals are used to determine the correct pair to spark first. After the crankshaft position signals have been processed by the IC module, it sends a fuel control reference pulse to the PCM. When the PCM receives this pulse it will command all eight injectors to open for a priming shot of fuel in all cylinders. After priming, the injectors are left OFF for the next eight fuel control reference pulses from the IC module (two crankshaft revolutions). This allows each cylinder a chance to use the fuel from the priming shot. During this waiting period, a cam pulse will have been received by the PCM. Now the PCM begins to operate the injectors sequentially based on true crankshaft position. However, if the cam signal is not present at start-up, DTC P0340 will set and the PCM will start fuel delivery in a random pattern with a 1 in 8 chance that fuel delivery is correct. The crankshaft position sensor signals are used only by the IC module. It is used for spark synchronization and to initiate reference pulses only (not passed to the PCM).

DIAGNOSTIC AIDS
Perform the Powertrain OBD System Check before performing this chart to help prevent mis-diagnosis. Testing and Inspection