Hello, so to begin. My car was not starting, told my fuel pump, replaced twice and nothing. Found out about inertia switch and changed it, now car runs.

Before this switch blew out my car was running perfectly, no check engine, nothing. Now i have changed my fuel pump twice and put a brand new fuel filter in and soon after i get lean codes P0171 and P0174. My fuel pressure is 60psi at idle and drops to 0 after about 30 seconds when the car is shut off.
Alot of my intake is new since i did have a vacuum leak before, so i do not suspect that is it, especially since this happened after the new fuel pump. I am completely stuck as to what i should do so any help would be appreciated! Thanks!

Oh and i get hesitation when trying to accelerate sometimes

 

To replace the fuel pump you have to drop the tank. And if you have to drop the tank, you have to disconnect evap lines. Maybe they didn't get hooked back up when the fuel pump was replaced but I would expect evap codes if that were the case. It doesn't cost you anything to take a look.

I'd still be looking for leaks on/around the intake. Check all of your other vacuum lines and make sure there are no leaks between the MAF and the intake manifold. Since both banks are lean, it would take a leak on both sides of the lower intake or a vacuum leak at an injector on each bank. Doesn't seem likely but I suppose it's still possible.

In addition, I would clear the codes and remove the battery cable to clear the memory to let the PCM relearn and see if the codes return.

 

codes 171 and 174 normally point to a vacuum leak... but in your case I might be fuel pump related.. You say the pressure drops to 0 psi shortly after shutdown. That should not happen. You should retain pressure for a few hours after shutdown. Should be a check valve on the pump that takes care of that. Om not sure if the 60 psi running pressure is correct or high......... are you sure you got the right pump ? You didn't worn on a pressure regulator under the hood ?? I don't know about the EXP, but some F!50 have a pressure regulator on the fuel rail near the fire wall. That regulates the pressure and dumps back to the tank any extra.. If it is " stuck" it could leak off after shutdown.

 

You've been dealing with this problem since earlier this year. I remember your post about it on explorerforums.

Your fuel pump pressure needs to be within the 75 to 90psi range.

One thing I have found while searching about fuel related issues on the first generation Sport Trac is the fuel damper on the fuel rail. In appearance it looks like a fuel pressure regulator.






Make sure there's is no fuel leaking from it. When these dampers start to fail they let the fuel pressure bleed down (the same symptom of a bad regulator on the fuel pump assembly).