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fuel pressure regulator replacement

54843 Views 40 Replies 24 Participants Last post by  slimpartywagon
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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)
running rich
rough idle
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.

Step 1: 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.

Step 2: 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.

Step 3: 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. :thumbup
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Great write up man.. :thumbup
Nice write up! My Bronco is having the same symptoms. I broke the vaccum line going from the regulator to the upper intake. I replaced the hose with a rubber one...will that make a difference? The problem occurred after I broek and replaced that line. The regulator is not that old...maybe 1 1/2 years.
Perfect write up.....VERY concise and clear!
Nice write up! My Bronco is having the same symptoms. I broke the vaccum line going from the regulator to the upper intake. I replaced the hose with a rubber one...will that make a difference? The problem occurred after I broek and replaced that line. The regulator is not that old...maybe 1 1/2 years.
well, if i understand you correctly, you were not having any problems until after you replaced the vacuum line with the rubber hose. so my guess would be that it is making a difference. the vacuum lines must have very tights connections and no leaks in order the deliver the fuel correctly. leaks in the vacuum lines will cause you to run rich and idle roughly. i'd suggest taking out the rubber hose and putting in a new vacuum line.
man, wish this was up a few months ago. could have saved me a shitload of money and headaches.
Thinking about changing my FPR as a matter of mantainence, I've had the 1986 FSB for 2 years now and don't know how old it is. It has the oem Ford oval on it & looks almost new and clean but it probably wouldn't hurt to replace it. It's right there on the top and doesn't look to hard to do.

What's with the screws upside down?
Can I use the schrader valve to release pressure to do this?
Are the screws phillips or allen?
Thanks

:chili: I grew up in Montclair NJ, been in CA 30 years!
Can this be done on an 1984 with my carburator? i have the same symptoms as you had...
JKossarides said:
Thinking about changing my FPR as a matter of mantainence, I've had the 1986 FSB for 2 years now and don't know how old it is. It has the oem Ford oval on it & looks almost new and clean but it probably wouldn't hurt to replace it. It's right there on the top and doesn't look to hard to do.

What's with the screws upside down?
Can I use the schrader valve to release pressure to do this?
Are the screws phillips or allen?
Thanks

:chili: I grew up in Montclair NJ, been in CA 30 years!
1) Its a Ford thing
2) I think you would want to release pressure via the enertia switch...on my 86 it is located in the cab underneath the where the radio is. square box with a button...push the button.
3) Allen
SO... Yes no maybe!? i'm dying here...
I don't believe a carbed Bronco has an FPR like an EFI one does.
jermil01 said:
I don't believe a carbed Bronco has an FPR like an EFI one does.
I agree.
ouch... so i have to switch the Carb...
Xris: Hey 86 Buddy what's happening! My inertia switch is under the dash/radio too.
I recently changed my fuel filter just using the schrader valve and that worked ok, but you say use the intertia, pop it up first, crank a few times then pop it back down when finished with FPR?

:thumbup

Thanks!
Great writeup:thumbup

Im replacing mine this week sometime (its an 88,) happen to know where my enertia switch/fpr are located?
JKossarides said:
Xris: Hey 86 Buddy what's happening! My inertia switch is under the dash/radio too.
I recently changed my fuel filter just using the Schroeder valve and that worked ok, but you say use the inertia, pop it up first, crank a few times then pop it back down when finished with FPR?

:thumbup

Thanks!
Yeah I did the same thing the first time with the Schroeder valve and it worked just fine. If I recall, you just push on that button on the inertia switch and it should relieve the pressure. Once relieved you should be able to do any fuel-related work. Just crank it up to build pressure again!

Nothing new in the 86 realm, although I hope to get the last parts (rear quarter and new tailgate) to start the rebuild. I'm starting to get big holes behind the door and rear wheel. May have to do a patch job to make it look pretty for awhile! PM me to let me know how things are in your world!
Xris: Thanks, I'll probably do it this weekend! I just drilled out the pop rivets to the elec door lock actuators, got tired of messing with it and couldn't lock the passenger side when I go to the gun club on Sundays. Took off the door panel and lubed the [email protected]#* out of it & now it works perfect. Not sure if I want to fix elec pw motors either I may consider finding some cranks for less maintenance. Working on these old Bronco's can get old after while, it's like you never get caught up!

Talk to you soon ~

:rockon
OK, FPR piece of cake! Since I didn't have to trigger the inertia switch for the fuel filter and the Bronco sat from noon until 5p.pm. It was getting late and I really wanted to get this done, so I did straight up. NO pressure, no squirting etc just a dribble from the old FPR. It's a PITA job because of the location and those allen screws upside down! Other then that it was easy. I just had enough clearance with one of the ejectors so as not to unhook it to get to one of the screws and the one in the back AGGGGGGGGGGGGGHHHH!

I was sweating and my glasses kept slipping down making it hard to see and the drop was hot so close to my hand, I did turn it off when I took the FPR off so as not to catch on fire OK. lol lol

I will make a tool for this by cutting down an allen wrench and fitting into a smalll socket with a small rachet to make this much easier. I took it for a test drive and checked for leaks running and not running and it runs smoother so the more we change these components the better the Bronco's run for sure. Next project is my 02 sensor!!!!!!!! Not looking forward to that because of the location but it's got to be done.
I can't say it enough here, but THANKS for all the input and pictures you all post on all these threads, it makes working on the Bronco's a lot easier for everyone, a real luxury to have this site.

Thank You

:enforce :enforce :enforce
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