Section 10-01A: Fuel Tank, Filters, Tubes and Electric Fuel Pump, Gasoline Engines | 1996 F-150, F-250, F-350, F-Super Duty and Bronco with Gasoline Engines Workshop Manual |
When the ignition switch (11572) is turned to the ON position, the Electronic Engine Control (EEC) power relay is energized and provides power to both the fuel pump relay and a timing device in the powertrain control module (PCM) (12A650). Fuel pump power is provided through the contacts of the fuel pump relay and the inertia fuel shutoff switch. If the ignition switch is not turned to the START position within approximately one second, the timing device in the powertrain control module will open the ground circuit (No. 97 T/LG) to the fuel pump relay. Opening the ground circuit de-energizes the fuel pump relay (opening its contacts), which de-energizes the fuel pumps. This circuitry pressurizes the fuel system.
When the ignition switch is turned to the START position, the powertrain control module energizes the fuel pump relay to provide fuel while cranking.
After the engine (6007) starts, the ignition switch is returned to the RUN position, the power to the fuel tank sending unit and pump is supplied through the fuel pump relay. The powertrain control module senses speed and shuts off the fuel pump by opening the ground circuit (No. 97 T/LG) to the fuel pump relay if the engine stops or engine speed drops below 120 rpm.