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1G Ideas for Sleeper FPR Setup

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TheBrownMike

5+ Year Contributor
54
61
Apr 9, 2018
SAN DIEGO, California
I'm looking to piece together a sleeper AFPR setup. My goal is to be able to run enough fuel (Wally 255) to support some decent HP (350+) with "stock enough" appearance that wouldn't catch your eye normally.

My original idea was just black AN fittings and braided line and tucking the AFPR somewhere lower on the firewall where it wasn't obvious, but Id like even more OEM looking if possible.

Thoughts? Ideas?

Current setup is SD with MAF removed. MAP sensors are under brake resi and in between intake runners. OEM looking overflow is on the list too...
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Could always gut/hollow out and plug up a factory fpr diaphragm, using it as a pass through, then run the line to the AFPR mounted lower on the firewall or under the intake manifold?
 
The stock one will support more power than you are looking to make.
 
It does. I have been using it on my daily 2g with 340L pump. Perfect for 300-350hp sleeper. It is just the return line direction is different.

You're mistaken/tuning around the issue. They evo FPR isn't really an upgrade. Most think it is because they fail to realize the Evo uses a duel pump voltage setup to limit flow at low load so overrun doesn't happen at idle. It doesn't work that way for the DSM.

Evo guys that rewire 255 pumps(bypass the low voltage line) have overrun issues .
 
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You're mistaken/tuning around the issue. They evo FPR isn't really an upgrade. Most think it is because they fail to realize the Evo uses a duel pump voltage setup to limit flow at low load so overrun doesn't happen at idle. It doesn't work that way for the DSM.

Evo guys that rewire 255 pumps(bypass the low voltage line) have overrun issues .
If you believe so. I don't need to argue about tuning or so. I just speak and share my own experience that I did by myself. I mentioned this because the op said "stock enough appearance" and his car is 1g turbo manual. This was a kind of common upgrade in japan with manual gvr4 guys back in 90's. gvr4 have the same fpr as the 1g turbo manual, even on the late gvr4 with a 16g/510cc. Long time ago I was told this modification by a Japanese old rally driver who belonged to Mitsubishi and built his independent rally/dirt track shop. IIRC the one I am using is from an EVO5 or 6, perhaps EVO4. and doesn't over run, everything controllable/stable even with a 20 years old AFC, even not with a blue screen. After late 90s actually there is no much point to do this since performance parts including AFPR got way cheaper and easier to buy and works better. The stock would be fine but I did this because I had it and wanted to see the result.
 
I ran a stock FPR on my 92 with a 255 rewired in the tank. It never overran it but maybe I was just lucky.
BEAUTIFUL car buy the way!!! :thumb:
 
Agree with above, I'd run a 255 with stock FPR on plenty of setups just fine. Only went to an FPR when I did the 450 pump. Another variable is fuel. If you're running E85 you're returning less fuel to the tank at low throttle.
 
OP, what are you going to do about a FP gauge? I mounted my gauge with an adaptor on the stock fuel filter and thinking maybe its restricting flow. I too am looking to clean things up as much as possible.
 
You could always mount an inline gauge, like those of us that now have AFPR's, in the return line in an inconspicuous spot if you need a pressure gauge. In the return line there isn't a chance of restricting fuel to the injectors, if you are worried about that.
 
A mini black fuel lab AFPR mounted lower on the firewall would be pretty inconspicuous.

https://stmtuned.com/collections/su...ducts/fuelab-mini-fuel-pressure-regulator-6an
This is what I had originally planned, I have the smaller Aeromotive "bypass" FPR that I was going to use, but wanted to go more stealthy. Still a possibilty though...

You could keep the stock FPR and adjust the voltage to the pump. I have details in this post of how I did it.

https://www.dsmtuners.com/threads/my-fuse-box-relocation-project-log.298569/page-30#post-153597070
This looks like a solid solution, able to run a bigger pump without over running on the low end.

I ran a stock FPR on my 92 with a 255 rewired in the tank. It never overran it but maybe I was just lucky.
BEAUTIFUL car buy the way!!! :thumb:
First off, Thank you! When I threw the 255 in it was running stupid rich at idle even without the rewire. My previous GSX didnt have an issue with it, but this one does.

I'm pretty sure that the stock FPR could easily support my power goals, however I would just like to keep it running as properly as possible (not overly rich at idle). As for a FP gauge, I would probably go with a tap (schrader valve) where I could screw on a temporary gauge for tuning, then remove it once its dialed.
 
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