Topic: Fuel Pressure Regulators

[Jeffy]

a few things need to be considered when choosing an injector. the ones you see referred to as 19# injectors are actually 18.4lb/hr (or something like that) but the pressure at which they are rated is 43.5psi. your YJ runs at 39psi - the resulting flow is less than stock if you install those injectors. They are also a different type, the design III have 4 holes and are disc compared to pintle on the stock ones (design III are better than stock). if your goal is more power you need to look for an injector that flows between 5 to 10% more than the stock ones so your result is reasonable and not flooding the engine with fuel. the alternative is an adjustable fuel pressure regulator, hesco makes direct fit ones - increasing the fuel pressure will increase the fuel delivery at wot (wide open throttle). for best results a combination of the 2 would work, design III injectors and and adjustable FPR. i don't have an injector p/n that i know for sure will give you the result you're looking for just by itself but you can research and use an online injector flow calculator (google that) to determine the resulting flow on the YJ fuel pressure.

This brings up a related subject.  Why not convert the Jeeps system to a 43.5psi system with a OEM pressure regulator.  It's a lot cheaper then buying the Hesco adj..

[sharpxmen]

This brings up a related subject.  Why not convert the Jeeps system to a 43.5psi system with a OEM pressure regulator.  It's a lot cheaper then buying the Hesco adj..

that would work - is there a direct fit FPR at 43.5psi?
the adjustable hesco is preset for 44psi i think, so same ballpark.

[Jeffy]

that would work - is there a direct fit FPR at 43.5psi?
the adjustable hesco is preset for 44psi i think, so same ballpark.

I've been hearing that there is but I haven't looked into it.

[Jeffy]

This guy seems to know what he's talking about.  I've seen his original posts elsewhere as well.

http://www.jeepforum.com/forum/f12/diy-fuel-injectors-clean-904158/

The FPR part #:

ACDELCO 2172151
AIRTEX 5G1087 aftermarket
BIG A 82-211 aftermarket
BIG A 82-24 aftermarket
BORG WARNER 23021 aftermarket
CHRYSLER 4418850 OEM
CHRYSLER 5277829 OEM
CHRYSLER 5277864 OEM
DELPHI FP10046 FP10072
ECHLIN 2-19681 aftermarket
FILKO PR-144 aftermarket
FILKO PR-215 aftermarket
GP/SORENSEN 800-136 aftermarket
GP/SORENSEN 800-323 aftermarket
KEM 143-611 aftermarket
KEM 143-614 aftermarket
NIEHOFF 23021 aftermarket
STANDARD PR211 aftermarket
STANDARD PR24 aftermarket
TOMCO 21132 aftermarket
WELLS PR320 aftermarket
NAPA 219681

And here is a complete list of the cars these FPR can be found in:
Delivery Years
CHRYSLER CONCORDE V6 3.5 F FI 1993-1995
CHRYSLER CONCORDE LX V6 3.5 F FI 1996-1997
CHRYSLER CONCORDE LXI V6 3.5 F FI 1996-1997
CHRYSLER DYNASTY V6 3.3 R FI 1991-1993
CHRYSLER IMPERIAL V6 3.3 R FI 1990-1991
CHRYSLER IMPERIAL V6 3.8 L FI 1991-1993
CHRYSLER INTREPID V6 3.5 F FI 1993-1997
CHRYSLER INTREPID ES V6 3.5 F FI 1995-1996
CHRYSLER LHS V6 3.5 F FI 1994-1997
CHRYSLER NEW YORKER V6 3.5 F FI 1994-1996
CHRYSLER NEW YORKER FIFTH AVENUE V6 3.3 R FI 1990-1993
CHRYSLER NEW YORKER FIFTH AVENUE V6 3.8 L FI 1991-1993
CHRYSLER NEW YORKER LANDAU V6 3.3 R FI 1990
CHRYSLER NEW YORKER SALON V6 3.3 R FI 1990-1993
CHRYSLER TC MASERATI V6 3.0 S FI 1990
CHRYSLER TOWN & COUNTRY V6 3.3 R FI 1990-1993
CHRYSLER TOWN & COUNTRY V6 3.8 L FI 1994-1995

DODGE CARAVAN V6 3.3 J FI 1994-1995
DODGE CARAVAN V6 3.3 R FI 1990-1995
DODGE CARAVAN C/V V6 3.3 J FI 1994-1995
DODGE CARAVAN C/V V6 3.3 R FI 1991-1992
DODGE CARAVAN ES V6 3.3 R FI 1993-1995
DODGE CARAVAN LE V6 3.3 R FI 1991-1995
DODGE CARAVAN SE V6 3.3 J FI 1994-1995
DODGE CARAVAN SE V6 3.3 R FI 1991-1995
DODGE DYNASTY V6 3.3 R FI 1990-1993
DODGE DYNASTY LE V6 3.3 R FI 1990-1993
DODGE GRAND CARAVAN ES V6 3.3 R FI 1993-1995
DODGE GRAND CARAVAN ES V6 3.8 L FI 1994-1995
DODGE GRAND CARAVAN LE V6 3.3 R FI 1990-1995

DODGE GRAND CARAVAN LE V6 3.8 L FI 1994-1995
DODGE GRAND CARAVAN SE V6 3.3 R FI 1990-1995
DODGE INTREPID V6 3.5 F FI 1993-1997
DODGE INTREPID ES V6 3.5 F FI 1993-1997
DODGE SPIRIT L4 2.5 V FI 1994
EAGLE VISION ESI V6 3.5 F FI 1995-1997
EAGLE VISION TSI V6 3.5 F FI 1993-1997
PLYMOUTH ACCLAIM L4 2.5 V FI 1994
PLYMOUTH GRAND VOYAGER LE V6 3.3 R FI 1990-1995
PLYMOUTH GRAND VOYAGER LE V6 3.8 L FI 1994-1995
PLYMOUTH GRAND VOYAGER SE V6 3.3 R FI 1990-1994
PLYMOUTH GRAND VOYAGER SE V6 3.8 L FI 1995
PLYMOUTH PROWLER V6 3.5 F FI 1997
PLYMOUTH VOYAGER V6 3.3 J FI 1994-1995
PLYMOUTH VOYAGER V6 3.3 R FI 1995

PLYMOUTH VOYAGER LE V6 3.3 R FI 1991-1995
PLYMOUTH VOYAGER LX V6 3.3 R FI 1994
PLYMOUTH VOYAGER SE V6 3.3 J FI 1994
PLYMOUTH VOYAGER SE V6 3.3 R FI 1991-1995

[FourbangerYJ]

Do you think the 50 PSI would be to much? Seems the go from 41-50 PSI.
 I was looking at doing this a few months ago, there is a thread on this board somewhere.

[sharpxmen]

Do you think the 50 PSI would be to much? Seems the go from 41-50 PSI.
 I was looking at doing this a few months ago, there is a thread on this board somewhere.

yes, it's too much.

[Jeffy]

yes, it's too much.

At idle he says it's 41psi.

[FourbangerYJ]

At idle he says it's 41psi.

Idle = 41PSI
WOT = 50PSI
What PSI do you think 1/2 throttle would be? 45-46?

[sharpxmen]

Idle = 41PSI
WOT = 50PSI
What PSI do you think 1/2 throttle would be? 45-46?

it doesn't matter at 1/2 throttle - at that position you're in closed loop. you always calculate at wot where vacuum has no bearing and the pcm is in open loop (so there's no o2 feedback). but to answer your question at 1/2 throttle and 900 rpm can be 48psi but at 4000rpm can be 44 psi - \he same for the stock one (38 and 34 for example) so the absolute difference between the 2 would be the same if you compare at the same throttle pos and rpm - i had the supercharger on with that much pressure and was blowing black smoke so i still think it's too much - but i'll run some numbers later on and tell you the difference.

[Jeffy]

Ok, I split this off the other topic since we are getting into more specific things.

So the YJ's fuel pressure is 31 psi at the fuel rail and jumps to 39 psi when vacuum is applied.

• 31-39 psi

(*The TJ on the other hand, is regulating it to 49.2 psi +/-5 psi at idle.  This happened in 1996.)

Stock Injectors are rated at 17.4 psi @ 39 psi.  Ford 19 psi are 17.3 psi @ 39 psi.

So would we need a 33-42 psi FPR to get an actual 19 psi at the fuel rail?  Is that right?

[FourbangerYJ]

So would we need a 33-42 psi FPR to get an actual 19 psi at the fuel rail?  Is that right?

If that is the right pressures does such a FPR exist that would bolt right in?

[sharpxmen]

Ok, I split this off the other topic since we are getting into more specific things.

So the YJ's fuel pressure is 31 psi at the fuel rail and jumps to 39 psi when vacuum is applied.

• 31-39 psi

(*The TJ on the other hand, is regulating it to 49.2 psi +/-5 psi at idle.  This happened in 1996.)

Stock Injectors are rated at 17.4 psi  (at)  39 psi.  Ford 19 psi are 17.3 psi  (at)  39 psi.

So would we need a 33-42 psi FPR to get an actual 19 psi at the fuel rail?  Is that right?

to make it simple - if the 19# rating is at 43.5psi - that's what the FPR should be at (EDIT: to have that flow). My understanding is that they are less than 19lb/hr, so 44 it's ok.

you don't usually look at the idle pressure - it varies with the altitude and the health of the engine (how much vacuum is "seen" at the vac port by the FPR).

[Jeffy]

to make it simple - if the 19# rating is at 43.5psi - that's what the FPR should be at (EDIT: to have that flow). My understanding is that they are less than 19lb/hr, so 44 it's ok.

you don't usually look at the idle pressure - it varies with the altitude and the health of the engine (how much vacuum is "seen" at the vac port by the FPR).

So 44 psi would be WOT right?

[jfrabat]

I am interested in this as well...  I would love to increase FP, but the Hesco pricing makes it prohibitive, so let me know which is the right one (and preferably, before May, as I will be in the US then, and can probably have them sent to my friend's house where I will stay at in Miami).

[sharpxmen]

So 44 psi would be WOT right?

correct. if you have an adjustable one you just remove the vac port to set the wot pressure.