Hard Start

DEFINITION
Engine cranks OK but does not start for a long time. Does eventually operate, or may start, but immediately stalls.

PRELIMINARY CHECKS
- Perform a careful visual / physical check as described in Preliminary Checks. - Important Preliminary Checks
- Make sure the driver is using the correct starting procedure.

SENSORS
Engine Coolant Temperature (ECT) Sensor
Using a Tech 1 scan tool, compare engine coolant temperature with ambient temperature on cold engine.
If engine coolant temperature readings are 5 degrees greater than or less than ambient air temperature on a cold engine, check resistance in engine coolant temperature sensor circuit or sensor itself. Refer to Diagnostic Charts / DTC 15 Coolant Sensor Circuit and compare resistance value readings. Testing and Inspection

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 be able to control the idle speed. While monitoring TP sensor voltage the scan tool and/or voltmeter should display less than .85 volts with the throttle closed.

FUEL SYSTEM
CHECK:

- Fuel pump relay operation. Pump should turn "ON" for 2 seconds when ignition is turned "ON." Use Diagnostic Charts/ Chart A-5 Fuel Pump Relay Circuit Diagnosis.
- Fuel pressure, use Diagnostic Charts / Chart A-6 Fuel System Diagnosis. Testing and Inspection
- For water contaminated fuel.
- Fuel Pump Relay- Connect test light between fuel pump "test" terminal and good ground. Test light should be "ON" for two seconds following ignition "ON." If not , refer to Diagnostic Charts / Chart A-5 Fuel Pump Relay Circuit Diagnosis. Testing and Inspection

IGNITION SYSTEM
Check ignition system for:

- Proper ignition voltage output with spark tester J 26792 or equivalent (ST-125).
- Spark Plug problems; check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits.
- Bare or shorted ignition wires.
- Pick-up coil resistance and connections.
- Worn distributor shaft.
- Moisture in distributor cap.
- Loose ignition coil connection.
- CKT 423 (ignition control) for short to ground.

ADDITIONAL CHECKS
CHECK:

- IAC valve operation - refer to:Diagnostic Charts / C-Charts / Idle Air Control (IAC) System Check. Testing and Inspection
- Basic engine problem.
- Technical Service Bulletins for PROM updates.
- Exhaust Gas Recirculation (EGR) System operation.
- Use chart labeled Diagnostic Charts / C-Charts / EGR System Check. Testing and Inspection