SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSFORD1999MUSTANG GT, 2D CONVERTIBLE, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 24 (ENGINE CONTROLS - THEORY & OPERATION - GASOLINE & NGV)COMPUTERIZED ENGINE CONTROLSOUTPUT DEVICESFUEL PUMP (APPLICATIONS USING FUEL PUMP RELAY FOR FUEL PUMP ON/OFF CONTROL)
1999 Ford Mustang GT, 2D Convertible, Standard

Fuel Pump (Applications Using Fuel Pump Relay For Fuel Pump ON/OFF Control)

1999 Ford Mustang GT, 2D Convertible, StandardSECTION Fuel Pump (Applications Using Fuel Pump Relay For Fuel Pump ON/OFF Control)
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2002 Mercury Sable, 2002 Mercury Mountaineer, 2002 Mercury Grand Marquis, 2002 Mercury Cougar, and 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Fuel Pump (FP) is a PCM output signal that is used to control electric fuel pump. With PCM power relay contacts closed, Vehicle Power (VPWR) is sent to coil of fuel pump relay. For electric fuel pump operation, PCM grounds FP circuit, which is connected to coil of fuel pump relay. This energizes coil and closes contacts of relay, sending Battery Voltage (B+) through FP PWR circuit to electric fuel pump. When ignition switch is turned to ON position, electric fuel pump runs for about one second, but is then turned off by PCM if engine rotation is not detected. For applications with 2-speed fuel pumps, a normally closed low speed fuel pump relay is wired into fuel pump ground circuit. With low speed fuel pump relay contacts in normally closed position, there is no extra resistance in ground circuit, allowing high speed operation. For low speed fuel pump operation, PCM will ground Low Fuel Pump (LFP) circuit, which opens relay contacts, causing fuel pump ground circuit to pass through a resistor. See Fig 1. For additional fuel pump information, see FUEL DELIVERY  under FUEL SYSTEM (GASOLINE).

Fig 1: Identifying 2-Speed Fuel Pump Circuits
G00088421Courtesy of FORD MOTOR CO.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.