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FPR shim

8K views 41 replies 7 participants last post by  PSDfan99 
#1 ·
well i did the FPR shim today becouse my psi is about 56psi and would like closer to 65 psi. i used a BB and did eveything i was suspose to do,made sure the spring didnt get messed up or anything. got in the truck and my psi went up to 100 psi. so i took it apart and did 3 other time, tried differnt bb's and still hit 100psi. just wondering if i did something wroung. i took it out now becouse i no a 100 psi would likely scew something up. has anyone else had this problem. can i do anything else to achevie 65 psi?
thanks
 
#2 ·
Yeah.......I have read where you can use an allen head screw and grind the head down until you achive the desired pressure. I guess the threaded part of the bolt slips in the spring. Do a search I'm sure you will find something.



 
#3 ·
yeah i fourd the one two. i just dont have access to a grinder so that why i was trying the bb, but i dont no if that would either becouse i dont no if u could grind the head smaller then the size of a bb.
 
#4 · (Edited)
What year you got? Are you sure the bb is resting somewhat inside the opening of the spring? I took my fpr completely off so I could get it right. That way you can just drop the bb in and place the spring on top if it, also get the point in the middle of the brass bolt centered into the spring. Also clean the screen while you have it out, don`t forget the o-ring on the screen and the brass bolt if you decide to go that route. The bb size to use is 0.177 or 4.5mm which are the same.
 
#5 ·
i got a 2000, i took the cover off then pulled the spring and the brass thing out, place the bb down in the brass thing and put the spring back in and put the cover back on, and made sure the spring was in the center of it, then put the cover back on.. it seamed like it had alot of tension on it.
 
#6 ·
Pull the spring out, leave the brass thing in. Put a tiny bit of grease on the end of the spring and then stick the BB on the end of the spring. The grease acts as a "glue" to hold the BB so it won't fall off the spring while installing it. Then insert the spring inside the FPR mechanism in the bowl with the BB headed outward. The BB wants to be touching the FPR cap (the one that has the 2 torx bolts holding it on the bowl). If you do that, it should be fine.
 
#7 ·
i put the bb between the spring and the aluminum cover, i dont know if it would make any difference but id try it that way, spring,bb,cover(cap) and be careful when tightening the fuel line back onto the cap, if you tighten it to much you may crack the threads!
 
#8 ·
OK the hole the bb goes in is actually two holes. A big opening where you start to screw in the brass bolt. down inside and at the bottom of that is a smaller hole and it has a lip so if you don`t take the fpr off you will have to take a small screwdriver etc. to push the bb into the small hole then the spring also goes inside the small hole and sits there thats why you then have to line up the center of the bolt within the center of the spring to keep everything straight. If you are not having issues w/your truck, idle,throttle etc. I would forget it.
 
#10 ·
The FPR design is different on the OBS trucks like yours compared to the Superduties, if that is what your referring to.
 
#9 ·
I like the grease way PSDfan99 does it. much eisier.
 
#11 ·
yeah my fuel presure is at 58 and i did the bb and took it up to 100psi.. i put the bb down in the brass cup thing, do u think putting grease on it and putting in inbetween the cap and spring is going to be any different then what i have done. just wondering ? i will definately try it though becouse i would like to get it to about 65-68 psi.
 
#12 ·
you cant put it like that because the point on the bolt goes in there. He was talking about putting graese on the front end that goes into the hole to keep the bb from falling off the spring. Look if the bb is too big (what size are you useing?) it should be 0.177 or 4.5mm you are going to have to go with something smaller. Something solid etc. like grinding a small bolt head down etc. Did you put the spring in the same way it came out?
 
#13 ·
like i stated before..... the OBS trucks like YOURS has a different setup and the Superduties ARE different. The truck that this shim is going in is not an OBS, therefore the the cap wont have a "point" on the end of it. I know, I have done the FPR shims on OBS trucks and several superduties.
 
#14 ·
i am not sure what bolt you are talking about with a point on it, becouse on mine i take the fuel line off with just a fitting and there is 2 toques head bolts on either side. and it is a .177 bb. yeah i put the spring in just like it came out... here is the order i put it back in...in the pic
 

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#15 ·
this is a joke right? Your truck truck doesnt have the FPR setup that this other guy is taking about, hes confused....

Put the BB between the spring and the cap (the one with the torx bolts) and it should work out fine.
 
#16 ·
7.3f350 did it like this since I sent him the info and pic to follow:



This is the location I have put shims in the FPR on every truck I have done the shim on. No, DI use to sell a shim kit that put the shim in the cap so maybe there is something to it on some trucks.
 
#17 ·
naa mine dont have a point on it...i will try that way tomorrow but i what i am wondering is if it is going make a difference becouse the spring and bb are the same legnth either way. ya see where i am coming from and what i am saying.. i will do it becouse i want it to work but a part of me dont understand why it would be any difference.
 
#18 · (Edited)
George, try to put the BB on the other end of the spring. That is what Jake is trying to say. He might be onto something, it can't hurt to try. It may have something to do with the internal shape of the cup in the brass plunger. I will have to go play with the fuel bowl on the bench.
 
#19 ·
aight i will try in the morning and will post what happens... if the same thing happens(get 100psi) for the 4-40 bolt with head ground down work or would not be able to get it ground down smaller then the bb?
 
#21 ·
you will be able to grind it down, I had the 4-40 bolt in my truck before I switched to the BB. The bolt is basically a trial and error method to get the fuel pressure where you want it. You will need to keep taking the FPR cap off to grind a little bit more off until you get it where you want it. I'll try to find the old 4-40 bolt I had inmy rig and take a pic. of it and post it so you can see what it should look like, but I may have thrown it away so no promises.
 
#20 ·
It will gind down smaller than the BB. I have done it. Just use vise grips on the threads to keep from betting burned. Don't ask.

Make sure the threads are only about 3/16" long. Any longer and it can cause problems
 
#22 ·
aight that would help, howard: about how much of the head should i leave, i only want around 10-12 psi gain.
 
#23 ·
.075" is the shim I used to get 73psi
 
#24 ·
I stand corrected, thanks for wiseing me up, I thought his truck was the same as mine and I wanted to help if I could but looks like I got in the way. I thought I was in the 94-97 threads. Will be more careful next time about the models we`re discussing etc.
 
#25 ·
aight so you think like .065 might give me somewhere around 65 psi?
 
#26 ·
I would start with .075" and see. You can always file or grind from there. Or just start at .065" and see as well. You will have to make the call.
 
#27 ·
aight i will do it.. i dont no if i be able to do that tomorrow or not becouse i dont have a grinder up here at my apt at school. but i will try the bb with the grease tomorrow and see if that makes a differnece.
 
#28 ·
also just wanted to say thank you to everyone that helped me out.. we did 3 pages of replys in like 3 hrs.. i thought that good..but anyways
thanks alot
 
#29 ·
well didnt get a chance to get it today but hopefully tomorrow i will be able to..i washed waxed it today though..so it looks really nice and clean...
 
#30 ·
Gillete Diesel has a spring, De fuser has a shim kit and you could do the wood screw method, where you grind the screw to fit the spring and tighten it to adjust the pressure or you could get regulated fuel system. Just some other alternatives for you.
 
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