Hard to Start

SYMPTOM DESCRIPTION:
Engine cranks OK, but does not start immediately. Will eventually start and run, but may die shortly after.



SYSTEM OR COMPONENT TO CHECK ACTION

COMPUTER INPUTS/OUTPUTS CHECK: ^ COOLANT TEMPERATURE SENSOR (CTS)
Using "Parameter" data, compare coolant temperature
with ambient temperature on a cold engine.
If coolant temperature reading is 5 degrees
more than or less than ambient air temperature
on a cold engine, check for high resistance in
coolant sensor circuit or sensor itself.
^ THROTTLE POSITION SENSOR (TPS)
If a sticking throttle shaft or binding linkage
causes a high TPS voltage (open throttle
indication), the ECM will not control idle.
Monitoring TPS voltage using a voltmeter should
read less than 1.25 volts with throttle closed.
^ IDLE SPEED CONTROL (ISC).
Refer to DIAGNOSTIC CHARTS/COMPONENT TESTING
(C-CHARTS) and A-CHARTS.
^ No crank signal.
^ PROM/MEM-CAL updates. Refer to
appropriate "Parameter Display" for proper PROM I.D.
^ MAT for proper operation.
^ MAP for proper operation.



FUEL NOTE: ^ Fuel pump relay operation.
Pump should turn "ON" for 2 seconds when
ignition is turned "ON." Use CHART A-5 in
DIAGNOSTIC CHARTS/A-CHARTS.
^ FUEL PRESSURE: use CHART A-4A in
DIAGNOSTIC CHARTS/A-CHARTS
^ WATER CONTAMINATED FUEL
^ FAULTY IN-TANK FUEL PUMP CHECK VALVE:
This could allow the fuel in the lines to drain
back to the tank after the engine is stopped.
To check for this condition:
1. Ignition "OFF."
2. Disconnect fuel line at the filter.
3. Remove the tank filler cap.
4. Connect a radiator test pump to the fuel line
and apply 103 kPa (15 psi) pressure.
If the pressure will hold for 60 seconds,
the check valve is OK.
^ FUEL PUMP RELAY - Connect test light between
fuel pump "test" terminal and ground.
Light should be "ON" for 2 seconds
following ignition "ON.".








IGNITION CHECK: ^ Proper ignition voltage output with
spark tester J26792 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 connections.
NOTE: If engine starts, but then immediately stalls,
disconnect the set timing connector. If engine
then starts, and runs OK, replace distributor
pickup coil.
^ EST CIRCUIT 423 for short to ground.





EMISSIONS CHECK: ^ EGR SYSTEM: Valve operation.
NOTE: Refer to EMISSION CONTROLS for testing procedures.