Chart A-3 Engine Cranks But Will Not Run

CIRCUIT DESCRIPTION
Before using this chart, battery condition, engine cranking speed, and fuel quantity should be checked and verified as being OK.

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 battery voltage and ignition voltage supplied to the ECM. No ALDL data may be due to an ECM problem. CHART A-2 will diagnose the ECM. If TPS voltage 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" tool should indicate engine speed during cranking.
2. If engine speed was indicated during crank, the ignition module is receiving a crank signal, but no spark" at this test indicates the ignition module is not triggering the coil or there is a secondary ignition problem.
3. The test light should flash, indicating the ECM is controlling the injectors. The brightness of the light is not important. However, the test light should be a J 34730 or equivalent.
4. 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 battery voltage on CKT 430, a reference pulse should be generated. If engine speed is indicated, the ECM and wiring are OK.
5. This step checks for ignition voltage at the injector harness connector. Disconnect harness connector before probing terminal "B." Reconnect connector after test.
6. Checks for open CKT 467 or 468 from connector to ECM. Be sure injector harness is connected.
7. Disconnect ECM C-D connector and check injector jumper circuits with a DVM.

DIAGNOSTIC AIDS
^ Water or foreign material can cause a no start condition during freezing weather. The engine may start after 5 or 6 minutes in a heated shop. The problem may recur after an overnight park in freezing temperatures.
^ An EGR sticking open can cause a low air/fuel ratio during cranking. Unless the system enters "clear flood" at the first indication of a flooding condition it can result in a no start.
^ Fuel pressure: Low fuel pressure can result in a very lean air/fuel ratio. See CHART A-7. Chart A-7 Fuel System Pressure Test