Hard to Start

Definition: Engine cranks OK, but does not start for a longtime. 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.

SENSORS
CHECK: Engine Coolant Temperature (ECT)
- using a TECH 1 scan tool, compare coolant with ambient temperature when engine is cold.
- If coolant or intake air temperature readings are 5 degrees greater than or less than ambient air temperature on a cold engine, check for high resistance in sensor circuit or sensor itself. Compare ECT resistance value to the "Diagnostic Aid" charts found within TROUBLE CODE CHARTS/CODE 15 COOLANT TEMPERATURE SENSOR CIRCUIT.
DTC 15
Throttle Position (TP) Sensor
- If a sticking throttle shaft or binding linkage causes a high TP sensor voltage (open throttle indication), the control module will not control idle. Monitor TP sensor voltage. Scan tool and/or voltmeter should display less than 0.85 volt with throttle closed.
Manifold Absolute Pressure (MAP) sensor.

FUEL SYSTEM
CHECK: Fuel pump relay operation. Fuel pump should operate from 2 to 20 seconds, depending on application, when ignition is turned "ON." Refer to CHART A-5 FUEL PUMP RELAY CIRCUIT DIAGNOSIS.
Chart A-5 Fuel Pump Relay Circuit Diagnosis
Fuel pressure. Refer to CHART A-6 FUEL SYSTEM DIAGNOSIS.
Related Tests, Information and Procedures
For water contaminated fuel.
Fuel pump relay.
- Connect test light between fuel pump "test" terminal and ground. Test light should be "ON" for 2 to 20 seconds following ignition "ON." If not, refer to CHART A-5 FUEL PUMP RELAY CIRCUIT DIAGNOSIS.
Chart A-5 Fuel Pump Relay Circuit Diagnosis

IGNITION SYSTEM
CHECK: Ignition system for:
- Proper ignition voltage output with spark tester J 26792 or equivalent (ST 125).
- Spark plugs; wet plugs, cracks, wear, improper gap, burned electrodes or heavy deposits.
- Bare and shorted wires.
- Moisture in distributor cap.
- Worn distributor shaft.
- Pickup coil resistance and connections.
- Loose ignition coil connections.
CKT 423 (Ignition Control) for short to ground.

ENGINE MECHANICAL
CHECK: For proper valve timing, low compression, bent pushrods, worn rocker arms, broken or weak valve springs, worn camshaft lobes.
Intake and exhaust manifold passages for casting flash.

ADDITIONAL CHECKS
CHECK: IAC operation - refer to C CHARTS/IDLE AIR CONTROL SYSTEM CHECK.
System Check - Idle Air Control (IAC )
EGR operation - refer to C CHARTS/EXHAUST GAS RECIRCULATION SYSTEM.
System Diagnosis - Exhaust Gas Recirculation (EGR) System
Service bulletins for PROM updates.