What is the fuel pressure regulator you ask?
Well, in a nutshell, it regulates the amount of fuel that is delivered from the tank to the engine. The fuel pump delivers a constant amount of fuel at a rate much greater than the engine could ever use under any conditions. The fuel pressure regulator simply allows the amount needed by the engine through and sends back the remaining fuel that is not needed.
Here is an out-of-focus side view of what the fuel pressure regulator looks like.
My symptoms that I experienced before the fuel pressure regulaor failed:
check engine light - code #173 (running rich right side)
delayed start-up (needing to give it gas to start, having to turn and hold the key for more than a few seconds)
Okay, now onto the replacement. Keep in mind this was done on my 1994 XLT with a 351 Windsor, your truck may or may not have the same set-up. In fact my regulator was different from the one that is typically found on 1994 Broncos, so check out the regulator before going to buy a new one.
You must first relieve the fuel pressure. To do this, first locate your inertia switch. Mine was located behind the right kick panel, but it could also be found on the driver's side of the firewall to the left of the brake pedal.
Behind the right kick panel.
It is a small housing with an electrical connection and a red button on the top of it. Once you have found the inertia switch, start your engine and let it run. You will notice that the inertia switch has a small slit just below the red button. Pop the red button up using a flat-head screwdriver through the small slit, it should cause your engine to stall. Or in my case, and your engine won't start, simply pop the button up without the engine running. Next, crank the engine a few times to be sure that all the pressure is released. Also unscrew the gas cap and leave off in order to help relieve the pressure. The fuel pressure is now relieved. Now, disconnect the cable on the negative terminal of the battery and the ground connections, for safety and to reset the computer codes.
Locate the fuel pressure regulator on the fuel rail.
This picture was taken from the driver's side front headlight towards the back center of under the hood.
Disconnect the vacuum lines from the regulator and remove the screws that are holding it in place. Be aware that the fuel rail may need to be removed in order to get to these screws on some models, I lucked out and had no problem accessing the screws and vacuum connections. You will need an allen wrench for the screws holding the regulator in place. A little fuel will most likely drain out, nothing to be worried about unless it's gushing out. Remove the regulator, but save the o-ring unless your new one came with another. Lightly oil the o-ring (do not use silicone grease) and replace with the new regulator. Secure the regulator in place with the screws and reconnect the vacuum lines.
Next, push the red button on the inertia switch back down. Reconnect the battery. Replace your gas cap. Turn your ignition on and off several times without starting the engine to check for fuel leaks. Finally, start the engine. It may take a few cranks in order to build up enough pressure for it to start. I'll also warn you that it may still run a little rough until the computer "re-learns" your truck's conditions, but will eventually smooth out unless you've got something else causing the rough condition.
And that's all folks! I decided to do a write-up because the fuel pressure regulator seems to be a part that commonly fails on Ford trucks and can be easily replaced by anyone. I tried to be descriptive yet brief, believe me it was hard for me not to write a novel. Hopefully this will help you guys out getting your beasts runnin smooth again. Feel free to PM me with any questions. Enjoy.