Cold Start Injector: Testing and Inspection

Chart A-9:

Chart A-9 Wiring Diagram:

CIRCUIT DESCRIPTION:

The cold start valve is used to provide additional fuel during the crank mode to improve cold start-ups. This circuit is important when engine coolant temperature is low because the other injectors are not "ON" long enough to provide the needed amount of fuel to start.

This circuit is activated only in the crank mode. The power is supplied directly from the starter solenoid and is protected by a fuse. The system is controlled by a cold start fuel injection switch which provides a ground path for the valve during cranking when engine coolant is below 95~F (350~C).

The cold start fuel injection switch consists of a bimetal material which opens at a specified coolant temperature. This bimetal is also heated by the winding in the switch which allows the valve to stay "ON" for 8 seconds at -20~C (-5~F) coolant. The time the switch will stay closed varies inversely with coolant temperature. In other words, as the coolant temperature goes up, the cold start valve "ON" time goes down.


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

1. Disconnecting the distributor 4-way connector will disable the other injectors. The amount of pressure drop depends on the temperature of the engine.

2. This test will determine the continuity through the switch to ground.