Shimming A FPR? How?
Diesel Fan
Joined: Jan 2010
Posts: 68
Likes: 6
From: Nampa, ID
For those that are curious about this "mod" with their other mods...this isn't really a modification and here's the reason why I say this.
Shimming the FPR is done in order to bring the fuel pressure back into the 'normal' range. Test your fuel pressure at the FPR schrader valve (looks like tire valve stem). If the pressure is between 40 - 80 PSI (for my '97 anyway), your fuel pressure is 'good'. If your pressure is lower than 40 PSI or very close to it (mine was around 45 PSI) you should probably go ahead and add the BB (not a ball bearing). You should be toward the upper end of the range mentioned, you're done.
Clean the FPR screen while you're doing this. Remove the bolts securing the FPR, pull back and you should see the screen toward the upper-right side of the FPR. Remove the cotton from cotton swab and GENTLY remove the built-up crud from the screen. Do not lose this screen. AFAIK, it cannot be purchased separately.
AFTER ADDING THE BB, TEST YOUR PRESSURE AGAIN! YOU DO NOT WANT TO GO ABOVE 80 PSI! THIS WILL CAUSE FUEL SYSTEM PROBLEMS THAT ARE NOT WORTH THE HASSLE.
I think Ford sells a kit that has a new spring and related parts, if you prefer that route. The BB causes compression of the FPR spring, in turn slightly raising the fuel pressure. I've heard of guys using two BB's to 'adjust' their pressure into the normal range.
You can get even fancier using a bolt and nut (or two) that fit inside the housing and spring to add adjustability to the FPR pressure setting.
I doubt you'll notice any HP gains. I did gain 0.5 MPG because I didn't have to use as much pedal input to get moving. With the few mods I do have, my combined average is between 16 - 18 MPG. I'll get about 12 - 14 MPG when towing my 24' travel trailer.
Shimming the FPR is done in order to bring the fuel pressure back into the 'normal' range. Test your fuel pressure at the FPR schrader valve (looks like tire valve stem). If the pressure is between 40 - 80 PSI (for my '97 anyway), your fuel pressure is 'good'. If your pressure is lower than 40 PSI or very close to it (mine was around 45 PSI) you should probably go ahead and add the BB (not a ball bearing). You should be toward the upper end of the range mentioned, you're done.
Clean the FPR screen while you're doing this. Remove the bolts securing the FPR, pull back and you should see the screen toward the upper-right side of the FPR. Remove the cotton from cotton swab and GENTLY remove the built-up crud from the screen. Do not lose this screen. AFAIK, it cannot be purchased separately.
AFTER ADDING THE BB, TEST YOUR PRESSURE AGAIN! YOU DO NOT WANT TO GO ABOVE 80 PSI! THIS WILL CAUSE FUEL SYSTEM PROBLEMS THAT ARE NOT WORTH THE HASSLE.
I think Ford sells a kit that has a new spring and related parts, if you prefer that route. The BB causes compression of the FPR spring, in turn slightly raising the fuel pressure. I've heard of guys using two BB's to 'adjust' their pressure into the normal range.
You can get even fancier using a bolt and nut (or two) that fit inside the housing and spring to add adjustability to the FPR pressure setting.
I doubt you'll notice any HP gains. I did gain 0.5 MPG because I didn't have to use as much pedal input to get moving. With the few mods I do have, my combined average is between 16 - 18 MPG. I'll get about 12 - 14 MPG when towing my 24' travel trailer.
Diesel Enthusiast
Joined: Dec 2009
Posts: 174
Likes: 9
From: waukesha, wi
did mine at 302k, noticed there is just a hint of more throttle response but nothing super, and its cheap and easy enough to do
Diesel Fan
Joined: Jan 2010
Posts: 68
Likes: 6
From: Nampa, ID
That's the beauty of this 'mod'. It's cheap and easy. You have the added benefit of having your fuel pressure back where it should be. I agree with the throttle response comment. After I did this, my truck just 'feels' better.
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