ok, first understand that your mechanic will only be able to check it when the car dies and wont restart immediately, otherwise it will test ok. to understand why fuel pumps fail, we have to understand how they work. They are located in the fuel tank and the fuel that pumps thru it also cools the fuel pump motor as well as keeps it lubricated. Low fuel often enough can cause the fuel pump to overheat and the start shutting down after a while on its own as it gets hot from running. This isnt a design flaw or Ford problem, as it happens in all makes of vehicles. and if an aftermarket fuel pump was installed instead of a genuine Ford one, then 3yrs is actually about a 1 1/2 longer than most aftermarket fuel pumps last. Due to the shortness of their lifespan, I wont install aftermarket fuel pumps anymore.
below is a photo of your engine
. I have labeled the throttle body, as well as air intake tube and a clamp. to spray starter
fluid into the throttle body, use a phillips head screwdriver to loosen the clamp I labeled. Then pull up on intake tube to release it from the air cleaner box it is attached to. Spray the starter fluid into the air intake tube, re-attach it and then try to start. takes maybe 5 minutes total time:
If no difference, then a voltmeter is required to test the coils, as well as other ignition system parts. the coiil and ingition control module are tested for receiving 12v and then for supplying 12v to the spark plugs
so that spark is achieved to ignitie the fuel in the cylinders.