FPR Shim problem,... need help
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Laughing Gas
Joined: Feb 2009
Posts: 921
Likes: 1
From: Denver CO
FPR Shim problem,... need help
I shimmed my FPR today. I went out and bought a brand new yet disposable slime brand dual head pressure gauge that went to 120 psi. (dual head was the only thing that went that high and the only brand at autozone) Checked my pressure it read 50 psi. I shimmed it with a standard BB. When I rechecked it read 90 psi. Now Ive always read 70 ist the goal and 80+ is too high. It seems to run fine so noticeable fuel leaks or O ring issues. Either way this concerns me. Unless I am checking the pressure diferently than you guys please advise. When I tested the pressure I held the gauge on it until it reached it maximum pressure and stopped 50 stcok and 90 after the BB shim. So what can you tell me, Im not entirely sure if theres another way to adjust down the pressure w/o removing the shim. What do you think / suggest?
Posting Guru
Joined: Nov 2001
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From: Ft Scott
90 is to high, anything over 60-65 is just extra wear and tear on the pump. Instead of a BB try using a 4-40 cap or phillips head screw.Insert the threaded end into the spring with the head facing the FPR cap. The tit on the cap will fit into the X or hex on the head and if the pressure is still to high you can file down the length to lower it.
Lead Driver
Joined: May 2007
Posts: 8,608
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From: Belair md
80 psi is the maximum fuel pressure ford allows, it is not too high, and i dont trust the tire pressure gauges as an accurate way to test your fuel pressure. if i check my fuel pressure with a tire gauge it shows anywhere from 45 to 100 psi yet if i hook up a real fuel pressure gauge i show 75-80 psi. i would file NOTHING untill you get a real gauge on it
Posting Guru
Joined: Nov 2007
Posts: 2,158
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From: West Texas
I wouldn't trust the tire pressure gauge either.
Also I seriousl doubt a true BB sized ball can make 90 psi. I just put a 3/16 steel ball bearing in mine and it got to 65. ALso the hole in the spool is supposed to be 3/16 inch but it's a couple thou under. I had to ream mine out on the lathe to make it the right size. It was just a nasty drill job from the factory full of burrs is all.
Is it possible that your BB is not fully in the bottom of the hole? Maybe the other end of the spring slipped off the little tit on the plug too.
Also I seriousl doubt a true BB sized ball can make 90 psi. I just put a 3/16 steel ball bearing in mine and it got to 65. ALso the hole in the spool is supposed to be 3/16 inch but it's a couple thou under. I had to ream mine out on the lathe to make it the right size. It was just a nasty drill job from the factory full of burrs is all.
Is it possible that your BB is not fully in the bottom of the hole? Maybe the other end of the spring slipped off the little tit on the plug too.
Post Fiend
Joined: Oct 2003
Posts: 5,903
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From: MICHIGAN
. You'll get enough info here to make you an expert in no time 
.FPR = Fuel Pressure Regulator. Theses guys are talking about making the fuel pressure a little higher than stock. It helps smooth out the isle and might add some throttle response. Here's more info...w/ pictures
https://www.ford-trucks.com/forums/5...mming-fpr.html
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Senior User
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From: Emmett, ID
I removed it...
Post Fiend
Joined: Oct 2003
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From: MICHIGAN
My FP is somewhere between 60-90 with a 3/16 ball bearing.
I agree wit the guys above, you need to check the FP with a known good gauge but it will still be a guess at the actual pressure. If you use a tire gauge...all you will see is the highest spike in the pressure.
The needle on a good FP gauge jumps around so much it's hard to see the actual FP.....
a glycerin filled gauge will slow the needle pulses down but may not show the highest/lowest pressures the pump is producing.
I agree wit the guys above, you need to check the FP with a known good gauge but it will still be a guess at the actual pressure. If you use a tire gauge...all you will see is the highest spike in the pressure.
The needle on a good FP gauge jumps around so much it's hard to see the actual FP.....
a glycerin filled gauge will slow the needle pulses down but may not show the highest/lowest pressures the pump is producing.
Postmaster
Joined: Jun 2007
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From: Rogue River, OR
If you use a fluid filled gauge you will get a more accurate reading. Also, as was already stated: if the springs slips off the tit on the inside of the brass cap it will allow the spring to develop a kink and you will get a high spike in the FP reading. Don't ask how I know this.
Rog
Rog
Posting Guru
Joined: Nov 2001
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From: Ft Scott
Joe,
Where did you find the 80 psi? Ive got a full set of factory service manuals and the PSD training manual and can't find that.
Where did you find the 80 psi? Ive got a full set of factory service manuals and the PSD training manual and can't find that.
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Laughing Gas
Joined: Feb 2009
Posts: 921
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From: Denver CO
If I were to guess I would say Its running around 70 psi. The first najor spike whe I put the guage on it tok it to 50 and the then up to 70 from there it took about 7 more spikes to get to 90. that being dome w/ a tire guage the ther was no resistance to bring the reading back down. I concidered putting a rubber band on the end of the guage w/ light tension to see what it would read with some return resistance for more of an average. What do you think? Also I ran it today around 35 -40 miles and never had any problems except what I know beleive is my turbo going out.
