Chart A-3 Engine Cranks But Will Not Run
Chart A-3 - Engine Cranks But Will Not Run:
Wiring Diagram For Chart A-3 - Engine Cranks But Won't Run:
CHART A-3 - ENGINE CRANKS BUT WILL NOT RUN
Test Description:
Engine cranks but won't run, or engine may start, but immediately stops running. Battery condition and engine cranking speed are OK. There is enough fuel in the tank.
1. A "SERVICE ENGINE SOON" light "on" is a basic check for ignition and battery supply to the Electronic Control Module (ECM).
2. Fuel spray from the injector indicates that fuel is available. However, the engine could be severely flooded due to too much fuel.
3. While cranking engine there should be no fuel spray with injector disconnected. Re ace the injector if it sprays fuel or drips like a leaking water faucet.
4. At this point the fuel system appears to be operating normally. Voltage at the spark plugs is checked using an ST-125 Spark Gap Tool. No spark indicates a basic HEI problem. If spark is OK the following checks should be made.
^ Throttle Position Sensor (TPS): If the sensor is sticking or binding in the wide open throttle position, the ECM will be in the "Clear Flood" mode. The air/fuel ratio will be 18:1 to 20:1, and this may be too lean to start a cold engine.
^ Coolant Sensor: If the sensor signal circuit "opens" with ignition off, the M will think the coolant temperature is -40~F, and provide fuel for this extremely cold temperature. The engine will be severely flooded, because the ECM cannot recognize an open circuit until the engine has been running for 1 minute or more. Check this circuit using Code 15 chart
5. The EFI system should be considered OK if no trouble was found. Reconnect injector and review Diagnosis By Symptoms - No Trouble Codes Stored for possible mechanical problems.
6. No fuel spray from injector indicates a faulty fuel system or no ECM control of injector. If the test light "blinks" while cranking, then ECM control should be considered OK. Be sure test light makes good contact between connector terminals during test. The light may be a little dim when "blinking". This is due to current draw of the test light. How bright it "blinks" is not important. However, the test light bulb should be an 1847 or equivalent.
7. No blinking light indicates no ECM control of injector. With Voltmeter selector switch in "AC Volts" position and voltage scale switch in the 2 volts range, voltage should be greater than .7 volt AC. If the voltage is less than .7 volt AC, there is an open or short to ground in HEI reference Circuit 430. If the circuit is ok, there is a basic HEI problem.
Chart A-4 - Engine Cranks But Will Not Run:
CHART A-4 - ENGINE CRANKS BUT WILL NOT RUN (CONTINUED FROM A3)
Test Description:
1. No fuel spray from one injector indicates a faulty fuel injector or no ECM control of injector. If the test light "blinks" while cranking, then ECM control should be considered OK. Be sure test light makes good contact between connector terminals during test. The light may be a little dim when "blinking". This is due to current draw of the test light. How bright it "blinks" is not important. However, the test light bulb should be an 1847 or equivalent.
2. Circuits 481 and 482 supply ignition voltage to the injectors. Probe each connector terminal with a test tight to ground. There should be a light on one terminal. If the test light confirms ignition voltage at the connector, then ECM injector control Circuit 467 or 468 may be open. Reconnect the injector, and using a test light connected to ground, check for a light at the applicable ECM connector terminal D14 or D16). A light at this point indicates that the injector drive circuit involved is OK.
If an ECM repeat failure has occurred, the injector is shorted. Replace the injector and ECM.