Chart A-3 Engine Cranks But Will Not Run
Chart A-3 Circuit:
Circuit Description
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.
Chart A-3 (Part 1 Of 2):
Test Description
Number(s) below refer to circled number(s) on the diagnostic chart.
1. A "Service Engine Soon" light "ON" is a basic test to determine if there is a 12 volts supply and ignition 12 volts to ECM. No ALDL may be due to an ECM problem Related Tests, Information and Procedures to diagnose the ECM. If TPS is over 2.5 volts, the engine may be in the clear flood mode which will cause starting problems. The engine will not start without reference pulses and therefore, the Tech 1 "Scan" tool should read rpm (reference) during crank.
2. No spark may be caused by one of several components related to the ignition system. Chart C-4 Ignition System Check to address all problems related to the causes of a no spark condition.
3. Fuel spray from the injector(s) indicates that fuel is available. However, the engine could be severely flooded due to too much fuel.
4. While cranking engine, there should be no fuel spray with injector disconnected. Replace an injector if it sprays fuel or drips like a leaking water faucet.
5. The fuel pressure will drop after the fuel pump stops running due to a controlled bleed in the fuel system. Use of the fuel pressure gage will determine if fuel system pressure is enough for engine to start and run.
6. No fuel spray from injector indicates a faulty fuel system or no ECM control of injector.
7. This test will determine if the ignition module is not generating the reference pulse, or if the wiring or ECM are at fault by touching and removing a test light to 12 volts on CKT 430, a reference pulse should be generated. If injector test light blinks, the ECM and wiring are OK.
Diagnostic Aids
Water or foreign material can cause a no start during freezing weather.
^ An EGR sticking open can cause a low air/fuel ratio during cranking.
^ Fuel pressure: Low fuel pressure can result in a very lean air/fuel ratio. Related Tests, Information and Procedures
^ A grounded CKT 423 (EST) may cause a "No Start" or a "Start then Stall" condition.
Chart A-3 Circuit:
Circuit Description
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.
Chart A-3 (Part 2 Of 2):
Test Description
Number(s) below refer to circled number(s) on the diagnostic chart.
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.
2. CKT 481 and CKT 482 supply ignition voltage to the injectors. Probe each connector terminal with a test light to ground. There should be a light "ON" at one terminal. If the test light confirms ignition voltage at the connector, the ECM injector control CKT 467 or CKT 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.