Mechanics

F150 FUEL PUMP

1991 Ford F-150

Electrical problem
1991 Ford F150 6 cyl Two Wheel Drive Manual 105000 miles

Truck won't start, when key is turned too on position the fuel pump runs the whole time key is on before it would shut off after a few seconds, plugs are new, but when I checked for spark they had a lot of carbon or soot on them, fuel filter new, pulled fuel line after filter turned on key there seemed like strong flow of fuel, behind intake manifold there is small fitting that looks like valve stem attached to fuel line, pushed it in fuel sprayed out under pressure
Avatar
Scarroll4406382
May 3, 2009.



The " valve stem" is the fuel pressure test point. Check the fuel pump relay !

FUEL CONTROL (GASOLINE ENGINES)
Precise fuel metering is accomplished with EEC-IV system. The ECA continually monitors engine operating conditions based on information received from various sensors and switches. In response to information received, ECA calculates optimum air/fuel mixture in relation to present engine operating conditions and affects required metering adjustments through output actuators control.
In the future, remember that discussion about fuel pumps, such as the following paragraph, belongs in the Fuel Delivery section. When ignition switch is turned to START position, ECA operates fuel pump relay to provide fuel for starting engine. ECA senses engine speed and shuts off fuel pump by opening ground circuit to fuel pump relay when engine stops or speed drops to less than 120 RPM. When ignition switch is in ON position, EEC power relay is energized (contacts closed). Power is provided to fuel pump relay and timer in ECA. Fuel pump receives power through fuel pump relay contacts.

Dave H
May 3, 2009.