Chart A-3 Engine Cranks But Will Not Run

Chart A-3 Engine Cranks but Will Not Run






Circuit Description

Numbers below refer to circled numbers on the diagnostic chart.
1. A MIL (Service Engine Soon) "ON" is a basic test to determine if there is a 12 volt supply and ignition 12 volts to PCM. No serial data may be due to an PCM problem and CHART A-2 will diagnose the PCM. If TP signal is over 2.5 volts, the engine may be in the clear flood mode which will cause starting problems. If engine coolant sensor is below -30° C, 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 ST-125 J 26792. No spark indicates a basic ignition problem.
3. Use an injector test light like J 34730-2B, or BT-8329A to test injector circuit. A blinking light indicates the PCM is controlling the injector.
4. This test will determine if there is fuel pressure at the CMFI unit and holding steady. Use fuel pressure gage J 34730-1. See CHART A-6. Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that may occur when installing the gage.

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.
- EGR valve stuck open.
- Low fuel pressure. Refer to CHART A-6.
- Water or foreign material in the fuel system.
- A ground CKT 423 (IC) may cause a "No Start" or a "Start then Stall" condition.
- Basic engine problem.