okay two questions. First what type of benifits can i gain from the fpr shim mod? (i have a 10k mod already done.) second what are the numbers on the air filter mod and where can i get one?

 

Search is your friend. Air filter is a 6637, Fleet Filters has the best price on them.

 

look at the recent post "thanks" by jimwilsonmasonry i just left detailed fpr instructions.

 

The FPR Shim is nothing more than bringing the fuel pressure back into spec. Your fuel pressure should be no more than 80psi. If it's down around 40psi, (like mine was), adding the shim (BB) will bring the pressure up. In my case, I went from 40psi to 70psi by installing the BB.

The engine runs quieter, idles smoother, and throttle response is much better. I gained about 1.5mpg by shimming the FPR and doing the NAPA 6637 air filter mod.

Check the links in my sig for pictures of one way to do the 6637 mod.

 

IDMooseMan when your fuel pressure was at 40psi did your truck Idle rough? was the rpm erratic at Idle ?

 

I wouldn't say she had an erratic idle, just a little rough. Of course, I didn't know I had a rough idle until AFTER I shimmed the FPR. At 40psi, she was just gutless.

I mean, I knew my rig was heavy, but I thought I'd have a little better "giddyup" in her. Much better after the shim. Less throttle to reach the same RPM and speed.

What's going on with your rig? (Hijack alert!)

 

IDMoose,


Help a noob out - What is the FPR Shim (and how is it done)?


Thanks,
CMOS

 

raises the fuel pressure. you shim the fuel pressure regulator with a round BB