Chart A-3 Engine Cranks But Will Not Run

Chart A-3 Engine Cranks But Will Not Run (Central MFI):

Ignition Circuit:

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

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart:

1. A Malfunction Indicator Lamp (MIL) "ON" is a basic test to determine if there is a 12 volt supply and ignition 12 volts to Powertrain Control Module (PCM). No serial data may be due to a PCM problem and Chart A-2 will diagnose the PCM.
If Throttle Position (TP) sensor is over 2.5 volts the engine may be in the clear flood mode which will cause starting problems. If coolant sensor is below -30°C (-22°F), the PCM will provide fuel for this extremely cold temperature which will severely flood the engine.

2. Voltage at the spark plug is checked using spark tester tool (J 26792). No spark indicates a basic ignition problem.

3. Use an injector test light like (J 34730-2B), to test each injector circuit. A blinking light indicates the PCM is controlling the injector.

4. This test will determine if there is fuel pressure at the Central Multiport Fuel Injection (CMFI) unit and holding steady. Use Fuel pressure gauge kit (J 34730-1). Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that may occur when installing the gauge.

DIAGNOSTIC AIDS
If no trouble is found in the fuel pump circuit or ignition system and the cause of a "Engine Cranks But Will Not Run" has not been found, check for:

^ Fouled spark plugs.
^ Exhaust Gas Recirculation valve stuck open.
^ Low fuel pressure.
^ Water or foreign material in the fuel system.
^ A grounded CKT 423 Ignition Control (IC) may cause a "No Start" or a "Start then Stall" condition.
^ Basic engine problem.

The PCM has ICs that are fault protected, therefore, if a circuit has failed, the IC may not be damaged and will keep the circuit open until the fault in the circuit has been corrected. When the fault has been corrected, reinstall PCM and check circuit. Replace PCM only if the circuit is still inoperative.