Hard to Start

DEFINITION: The engine cranks OK, but does not start for a long time. The engine does eventually run, or may start but immediately dies.

Preliminary Checks

- Refer to "Important Preliminary Checks." Testing and Inspection

- Make sure the driver is using the correct starting procedure.

Sensor Checks

- Check the Engine Coolant Temperature (ECT) sensor using the scan tool to compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 500 greater or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or the sensor itself. Refer to DTC P0117 or P0118 Diagnostic Aids. P0117
P0118

- Check the Throttle Position (TP) sensor. If a sticking throttle shaft or binding linkage causes a high TP sensor voltage (open throttle indication), the ECM will not control the idle. Monitoring the TP sensor voltage, the scan tool and/or voltmeter should display less than 1.25 (25%) volts with throttle closed.

Fuel System Checks

- Check the fuel pump relay for operation. The fuel pump should operate for 3 seconds when turning "ON" the ignition. Refer to "Table A-7A." Table A-7A Fuel System Diagnosis (Fuel Pump Relay Check)

- Check the fuel pressure. Refer to "Table A-7B." Table A-7B Fuel System Diagnosis (Fuel Pressure Check)

- Check for water contamination in the fuel.

- Check the fuel pump check valve. A faulty in-tank fuel pump check valve will allow the fuel in the lines to drain back to the tank after stopping the engine. To check for this condition:

1. Turn the ignition "OFF."

2. Disconnect the fuel line at the fuel filter

3. Remove the tank filler cap.

4. Connect a radiator test pump to the fuel line and apply 102 kPa (15 psi) of pressure. If the pressure holds for 60 seconds, the check valve is OK.

Ignition System Checks

- Check for the proper ignition voltage output with the spark tester J 26792 or equivalent.

- Check the spark plugs for the following:

- Terminal screw - bent, loose (rotate and pull)

- Ceramic Insulator - cracks, tracking, deposits (red or black dust)

- Tip Insulator - cracks, tracking, deposits (oil, carbon, glazing, fuel additive), loose (rattles)

- Center electrode - loose (wiggles side to side)

- Platinum pads - missing, wear, gap size (too large or too small)

- Check for bare and/or shorted ignition wires.

- Check for moisture in the distributor cap.

- Check for loose ignition coil connections.

- Check for a worn distributor shaft.

- Check the pickup coil and connections.

Additional Check

- Check the Intake Air Temperature (IAT) operation. DTC P0505. P0505

- Check for no crank signal.

- Check the EGR Valve operation. Check the Service Bulletins for ECM updates.