FUEL PUMP CONTROL (ELECTRIC)
When ignition switch is turned to "ON" position, EEC power relay is energized (contacts closed). Power is provided to fuel pump relay and to timer in ECA. Fuel pump receives power through fuel pump relay contacts. If ignition switch is not turned to "START" position, timer in ECA will open ground circuit after approximately one second. ECC senses engine speed and shuts off fuel pump by opening ground circuit to fuel pump relay when engine stops, or when engine speed drops to less than 120 RPM.
Opening ground circuit de-energizes fuel pump relay (contacts opened) and de-energizes fuel pump. This function allows pressurization of fuel system. When ignition switch is turned to "START" position, ECA operates fuel pump relay to provide fuel for starting engine while cranking.
FUEL PUMP RELAY
Fuel pump relay and ignition is activated by ECA when the ignition switch is in the "ON" or "START" positions. When ignition is turned on, the relay is activated to supply initial fuel line pressure to system. Some models use an Integrated Relay Controller Module (IRCM) which incorporates the fuel pump relay.
Monday, March 15th, 2010 AT 7:29 AM