Engine Cranks But Does Not Run
CHART 1 OF 2This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.
DIAGNOSTIC CHART
WIRING DIAGRAM
INSPECTION PROCEDURE
Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. A "Check Engine" Malfunction Indicator Lamp (MIL) "ON" is a basic test to determine if there is a 12 volt supply and ignition 12 volts to Engine Control Module (ECM). No Data Link Connector (DLC) may be due to an ECM problem and CHART A-2 will diagnose the ECM. If Throttle Position Sensor is over 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 "Scan" 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 will address all problems related to the causes of a no spark condition.
3. Fuel spray from the injector(s) indicated 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 control 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 B5, 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 Exhaust Gas Recirculation 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. See CHART A-7.
- A grounded CKT D4 (EST) may cause a "No-Start" or a "Start then Stall" condition.
CHART 2 OF 2
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.
DIAGNOSTIC CHART
WIRING DIAGRAM
INSPECTION PROCEDURE
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 Engine Control Module (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. The test light bulb should be a J 36400-1 or equivalent.
2. CKT A6 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 D16 or D14 may be open. Reconnect the injector and using a test light connected to ground, check for a light at the applicable ECM connector terminal "D16" or "D14". 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.