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 P0115 Diagnostic Aids. Testing and Inspection

^ 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 circuit opening relay for operation. Refer to "Table A-7A" for fuel pump circuit operation. Related Tests, Information and Procedures

^ Check the fuel pressure. Refer to "Table A-7B." Related Tests, Information and Procedures

^ 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 Idle Air Control (IAC) operation. DTC P0505. Testing and Inspection

^ Check for no crank signal.

^ Check the EGR Valve operation.

^ Check the Manifold Absolute Pressure (MAP) sensor scan tool parameter for being fixed, or slow response when throttle is snapped.

^ Check the Service Bulletins for ECM/PCM updates.