1999 expedition 5.4
A diagnostic said my fuel pump was going out. Had a mechanic replace pump and filter. It wouldn't start. Tried priming multiple times, still no start. Mechanic left with my repair manual to come back following weekend. No response. Took fuel filter off found very little gas in it. No idea how to check pressure but there's no hiss when I open fuel cap. All electrical stuff testing good. Have 7 gallon of gas in tank. Don't know what else to do. Please help
Your vehicle has what is called a "Fuel Pump Driver Module". That module gets it's signal from a fuel pump pressure sensor mounted on the fuel rail.
If pressure is low it gets full power, as pressure comes up it is pulsed to maintain a specified pressure .
We don't at this time know if the sensor is faulty or maybe something else is going on.
A capable scan tool would provide all that info , like desired and actual fuel pressure..
Those modules were mounted on a chassis cross piece and were known for corroding where contacting the frame cross member and not working. REPLACING the driver module solved the problem.A new mounting prevented that part from corroding..
If pressure is low it gets full power, as pressure comes up it is pulsed to maintain a specified pressure .
We don't at this time know if the sensor is faulty or maybe something else is going on.
A capable scan tool would provide all that info , like desired and actual fuel pressure..
Those modules were mounted on a chassis cross piece and were known for corroding where contacting the frame cross member and not working. REPLACING the driver module solved the problem.A new mounting prevented that part from corroding..
Last edited by hanky; Feb 15, 2025 at 04:40 PM.
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