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When diagnosing a fuel injected engine problem, one thing to keep in the back of your mind is that they do not have a "gas pedal", they have an "air pedal"
Carbs had an accelerator pump so when you pushed down on the gas pedal, extra gasoline was actually being squirted into the engine.
Fuel injection doesn't have this, when you press down on the gas pedal you get more AIR, not more fuel, computer adds more fuel but it is not instant, and pumping pedal does nothing but change air flow, nothing to do with fuel.
On the engine is the Fuel Pressure Regulator(FPR)
It is behind the alternator on 4.0l OHV Rangers
It has the Fuel Return Hose connected to it, AND a small Vacuum hose
Check that small vacuum hose for gasoline
If FPR leaks, raw fuel is sucked into the engine, flooding it out, so opening the "air pedal" would balance out the extra fuel being sucked in.
Leaking injector
All fuel injection computers have "Clear Flooded Engine" routine
Turn key on
Press "gas pedal" down to the floor and hold it down
This tells computer to Shut OFF fuel injectors, 0RPMs and WOT(wide open throttle)
Crank engine over, it should NOT start, it should not Fire at all, no fuel
If it starts or fires then fuel is leaking in
As soon as you release gas pedal injectors will start, or if RPMs get to 400 computer will exit Clear Flooded Engine
I use this every morning when starting my high mile '94 4.0l, I like to get oil pump circulating oil first, so I crank engine for 5 to 10 second and then release gas pedal for startup