Turning stock FPR into an AFPR

[eclipsh]

I've been working on turning the stock fuel pressure regulator into an adjustable unit. I've got some info up over on DSMTuners and thought I'd share it here as well.

http://www.dsmtuners.com/forums/cust...#post151994862

Chime in if you've got any ideas. If you've got some spare FPR's lying around I'd love to have 'em to mess with too. PM me if you have some extras you can part with. They're next to free at the bone yard but it is an hour drive from my house.

[DOHCstunr]

Hows the car running Nick?

[SPD_FRK]

This is something pretty common, but the information of how to do it is hard to find. A buddy at work discussed an adjustable FPR with me a few months back and said a lot of guys are doing something like this on their camaros even.

That link definitely helps us out given that they are using a Galant regulator, but heck even any regulator should work as long as it fits.

[Ivory8g]

another colorado member?

[phizzalot]

I've been reading up on that beefore you posted here eclipsh, but wasn't able to post to dsmtuners because of rules....

I would buy one pre-made by you when you get all the bugs worked out.. Nice mod keep em coming!!!!

[eclipsh]

Hows the car running Nick?

Still need to tune it. I'm running rich but I'm getting a lot of phantom knock from some very noisy lifters. I just need some free time to pull them and clean the gunk out so I can distinguish real knock from the imaginairy kind once I start tuning.

This is something pretty common, but the information of how to do it is hard to find. A buddy at work discussed an adjustable FPR with me a few months back and said a lot of guys are doing something like this on their camaros even.

That link definitely helps us out given that they are using a Galant regulator, but heck even any regulator should work as long as it fits.

Yeah, the problem for our regulators is the restrictor and finding a way to remove it. The metal is so tough drilling through it just isn't practical. Oh and the "they" in that thread is me :)

another colorado member?

Yup, down in Durango. I've been on here for a while. I've got a build thread up for my AWD Turbo build. I'm just not very active on here or DSMTuners anymore. I decided to go back to school for engineering-physics and I'm working 30+hours a week so I'm swamped :P

I've been reading up on that beefore you posted here eclipsh, but wasn't able to post to dsmtuners because of rules....

I would buy one pre-made by you when you get all the bugs worked out.. Nice mod keep em coming!!!!

Nah, I wouldn't want to sell them due to liability reasons. I posted up how I was building it so others can copy me with less hassle. You'll like the new one I came up with. It'll be a LOT easier to build. You'll just need a couple drill bits, a tap and a bolt. Haven't tested it yet but it should be super simple and effective.

[eclipsh]

Time for an update.

I decided I wasn't happy with the fluttering fuel pressure so I dug into the regulator I linked to above, tapped some more threads going up into the regulator body, center bored an 8 mm bolt with a 3/32" hole and threaded that up in to give the valve a better seat and more restricted flow to even out the pressure. I made the bolt short enough that I could thread my pipe fitting back onto the end and stick it back into the car. It evened out my pressure so the needle was barely wavering at idle (I'd estimate less than 1psi of flutter which is comparable to the stock regulator or an after-market one).

I ran with that for a while but decided I really wanted to make something cleaner. So I gave this idea another shot. I center bored another much longer bolt, polished the end for a nice mating surface, stuck a jam nut onto it, wrapped it in teflon tape and threaded it up into the regulator. I left enough of the bolt sticking out that I could slide the return line hose on over the end and clamp it down. Once it was in the car I adjusted the bolt in/out until I had the pressure where I wanted it and tightened down the jam nut. Before tightening the nut there was a little fuel leaking out while I adjusted the bolt. Once the jam nut was tight the fuel leak disappeared. I dried the regulator off and ran the car for a bit to see if any more fuel came out. I didn't get a drop and couldn't smell any gas leaking out. Just to be safe though I went ahead and soldered around the jam nut so nothing more could come out. I've been running that regulator in my car for a few days now. It is holding pressure better and starts up much easier. It takes less cranks than the Aeromotive AFPR I had on my 1g took to get going so I'll call that a victory. I still need to run my pressure gauge up onto the windshield and go boost it to see what happens but I'm sure it'll rise at a 1/1 ratio since I didn't mess with much of anything besides the center bore.

Here's what it looks like in the car.



Of course if you try this you do it at your own risk, I am not encouraging you to do so, just showing what I did. If your car burns to the ground it is your fault, you did it wrong and failed to properly test the regulator before installation.

[Shadow19]

basically this is the same concept as a adjustable BOV correct?

[eclipsh]

Sort of. The problem turbo Mitsu owners run into with the FPR is it gets over-run by large fuel pumps. Pressure rises too fast and fluctuates a lot if you put anything bigger than a Walbro 190 lph pump. This is caused by the tiny return line opening that I've removed. It is that little pill shaped thing I've pulled out.



What I did was remove this and replace it with a less restrictive return line (bigger hole). Really, the only reason to have the bolt thread in-out is to reset the base pressure where it should be. That is necessary because the little pill I've removed is placed at different heights in each regulator to tune the base pressure at the factory. The further up in the fuel cavity of the regulator the pill goes the more pressure is placed on it by the spring in the vacuum side of the regulator and the higher the base pressure rises. I just threaded the bolt in/out until I hit a base pressure I was happy with and will likely never need to mess with it again. That is the reason I soldered everything shut. It is added security against fuel leaks and I shouldn't have any reason to readjust the pressure in the future now that it is set and opened up to accommodate a bigger pump.

I'd also like to say that with more time spent running this regulator I still have no leaks and the regulator holds pressure for quite some time. Pressure drops very slowly now, at about 1-psi every minute or so.

[Shadow19]

Ah i gotcha. I see what youre talking about. So basically since i have a 190 lph walbro then im good?

[eclipsh]

Yup, you're fine until you go bigger.