Chart A-3 Engine Cranks But Will Not Run
Chart A-3 - Engine Cranks But Will Not Run:
Wiring Diagram For Chart A-3 - Engine Cranks But Will Not Run:
CIRCUIT DESCRIPTION:
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank. This chart should be used on engines using the Model 700 throttle body.
TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.
1. A "SERVICE ENGINE SOON" 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. If coolant sensor is below -30~C, the ECM will provide fuel for this extremely cold temperature which will severely flood the engine.
NOTE: For additional "A" Charts and Fault Codes refer to COMPUTERIZED ENGINE CONTROLS/DIAGNOSIS AND TESTING/DIAGNOSTIC CHARTS.
2. Voltage at the spark plug is checked using spark tester tool ST 125 (J26792) or equivalent. No spark indicates a basic ignition problem.
3. 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.
4. Use an injector test light like J34730, BT8329A or equivalent, to test injector circuit. A blinking light indicates the ECM is controlling the injector.
5. This test will determine if there is fuel pressure at the injector and that the injector is operating.
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 (EST) may cause a "No Start" or a "Start then Stall" condition.
^ Basic engine problem.