9D - Check Fuel Pulse Width (Fuel PW) While Cranking

9d. Check Fuel Pulse Width (FUEL PW) While Cranking






Purpose:
To verify that the Fuel Delivery Command Signal (FDCS) system is functioning correctly.

Recommended Procedure:
Install NGS Tester. Access FUEL PW PID on NGS Tester and monitor while cranking engine.

No fuel command signal when ICP, RPM and VPWR signals are correct usually indicates a loss of CMP sync signal. Refer to Pinpoint Test DF for CMP sensor diagnosis. Tests DF: Camshaft Position (CMP) Sensor

A 1-6 mS Fuel Pulse Width (FUEL PW) will be sent by the PCM to the IDM if system voltage does not go below 7 volts during cranking, engine cranking speed is above 100 rpm and injection control pressure is above 3450 kPa (500 psi). Even though a 1-6 mS fuel pulse width is shown on the NGS to be sent to the IDM, it is possible the IDM did not get the signal, due to a fault on either the CID or FDCS circuits or even the IDM. Note that low fuel pressure or no glow plugs could still be the cause of the No Start or Hard Start condition. A 0.60-mS fuel pulse width (a no fueling pulse) will be sent by the PCM when a sync pulse has not been received from the CMP sensor and if insufficient injection control pressure is present. This 0.60-mS fuel pulse width will not allow injectors to be enabled, but does keep the IDM and PCM synchronized until sufficient injection control pressure is realized.

Possible Causes:
- FDCS and CID circuitry
- PCM
- IDM

Tools Required:
New Generation Star (NGS) Tester 007-00500 or equivalent