Fuel Pump Control Test
When ignition is turned on, EEC power relay is energized, closing its contacts. Power is provided to both fuel pump relay and a timing device in EEC module. Fuel pump runs through contacts of fuel pump relay. If ignition is not turned on within 1 second, timing device in EEC module will create an open ground circuit.
Opening ground circuit de-energizes fuel pump relay (opening its contacts), which in turn de-energizes fuel pump. This circuitry provides for pre-pressurization of fuel system. When ignition switch is turned to "START" position, EEC module operates fuel pump relay to provide fuel for starting engine while cranking.