Fuel Pump Control

Fuel pump on/off and voltage variation control is accomplished through the ECU. Depending upon the system in use, control is accomplished by either varying voltage to the fuel pump or by turning fuel pump relay on or off. Some systems incorporate the air regulator and fuel pump on and off controls simultaneously.

Fuel pump on and off control takes place as follows:

• Ignition switch in "ON" position (operates for 5 seconds)
• Engine running and/or cranking and engine stopped (stops in one second).

Fuel pump voltage is approximately 9.4-13.4 volts except under the following conditions. Under these conditions, fuel pump voltage is approximately 13.4 volts:

• 5 seconds after ignition switch is turned off
• During engine cranking
• 30 seconds after engine starts
• High engine temperature with idle switch off
• Low engine temperature.