- Disconnect fuel line at high pressure pump inlet. Connect test hose and place in calibrated one-quart container. Disconnect wiring to high pressure pump. Replace fuel pump relay with modified test relay. See FORD 4-CYLINDER TUNE-UP article for information on relay modification.
- Ground, test relay, and energize pump for 10 seconds. If necessary, block end of fuel hose to prime pump. Measure fuel flow for 10 seconds. Check for inlet restriction or electrical circuit if volume does not meet specification.
Note. When checking suspect electric fuel pumps, ensure inertia switch has been reset and that there is adequate fuel supply. On the Bronco II and Ranger the inertia switch is located inside the cab, on the firewall, beneath the heater, forward of the right front door. It is located in the engine compartment on the Aerostar.