Part 1 of 2

Chart A-3 Wiring Diagram (1 Of 2):

Chart A-3 - Engine Cranks But Will Not Run (1 Of 2):

CIRCUIT DESCRIPTION
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.


TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. A "CHECK ENGINE" light "ON" is a basic test to determine if there is a 12 volt supply and ignition 12 volts to ECM. No ALDL may be due to an ECM problem and CHART A-2 will 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 "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) 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 faulty 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 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. See CHART A-7.
- A grounded CKT D4 (EST) may Cause a "No Start" or a "Start then Stall" condition.