Fuel Pressure Regulator

Justen · 12-28-2009, 03:27 PM

Just wondering if I really need and aftermarket Fuel Pressure Regulator for a Walbro pump, or should the stock FPR in the stock secondary rail be able to handle it?

Also, I know that the stock FPR has a vacuum line coming off of it, but I don't have anywhere to attach it to because I removed all of the solenoid valves when i took out all the emissions and rats nest. So i take it that the Stock FPR would not work correctly then?

Opinions? Do I need one now that my vacuum/boost solenoids are gone? Thanks

djmtsu · 12-28-2009, 03:50 PM

The stock FPR can handle a Walbro. You pull your vacuum source from the manifolds.

Read:

http://rotaryresurrection.com/2ndgen...s_removal.html

Specifically pay attention to this picture: (courtesy of rotaryresurrection.com)

antman0408 · 12-28-2009, 10:19 PM

My stock FPR crapped out after a couple thousand miles. I was getting 50 psi of fuel pressure all the time. I wouldn't worry about it until it does go bad, then replace it.

Justen · 12-29-2009, 01:50 AM

Quote:

Originally Posted by antman0408

My stock FPR crapped out after a couple thousand miles. I was getting 50 psi of fuel pressure all the time. I wouldn't worry about it until it does go bad, then replace it.

When they DO go bad, will they only let MORE pressure to be present??
...Just making sure, because I would rather not have the regulator starve the motor of fuel when it decides to fail, especially under boost

Max777 · 12-29-2009, 07:15 PM

What the FPR does, is lower the fuel pressure with more vacuum. At ide vacuum is high, and it pulls on the diaphragm in the FPR, letting more fuel flow back to the tank. When you have no vacuum, like under boost, the diaphragm restricts flow back to the tank, keeping lots of fuel in the rails, ready to go to the injectors.

While some FPR's increase fuel pressure with positive pressure on the diaphragm, I am not sure if the one on the RX-7 does so....

I have heard/seen people use an AEM adjustable FPR kit made for Hondas work on the S4 fuel pressure gegulators (has 2 bolts attaching it to the rail)

I would do some searching, and call AEM with stock fuel pressure specs, and measured frp dimensions, and ask them if they make any that would fit the rail. I have seen it done before, just cant find it...

12-28-2009, 03:27 PM	#1
Justen In Too Deep Join Date: Jun 2009 Location: Clifton, NJ iTrader: (3) Posts: 112 Rep Power: 16	Fuel Pressure Regulator Just wondering if I really need and aftermarket Fuel Pressure Regulator for a Walbro pump, or should the stock FPR in the stock secondary rail be able to handle it? Also, I know that the stock FPR has a vacuum line coming off of it, but I don't have anywhere to attach it to because I removed all of the solenoid valves when i took out all the emissions and rats nest. So i take it that the Stock FPR would not work correctly then? Opinions? Do I need one now that my vacuum/boost solenoids are gone? Thanks __________________ 1990 TII, fresh rebuild Atkins rebuild kit, RA apex seals Med. Streetport, TB mod, rebuilt turbo, ported wastegate, GodSpeed FMIC RacingBeat Turbo-back straight exhaust, Bonez test pipe, emissions/nest removed hks intake, Walbro, Profec B spec-2

12-28-2009, 03:50 PM	#2
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (10) Posts: 4,043 Rep Power: 21	The stock FPR can handle a Walbro. You pull your vacuum source from the manifolds. Read: http://rotaryresurrection.com/2ndgen...s_removal.html Specifically pay attention to this picture: (courtesy of rotaryresurrection.com) __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

12-29-2009, 07:15 PM	#5
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	What the FPR does, is lower the fuel pressure with more vacuum. At ide vacuum is high, and it pulls on the diaphragm in the FPR, letting more fuel flow back to the tank. When you have no vacuum, like under boost, the diaphragm restricts flow back to the tank, keeping lots of fuel in the rails, ready to go to the injectors. While some FPR's increase fuel pressure with positive pressure on the diaphragm, I am not sure if the one on the RX-7 does so.... I have heard/seen people use an AEM adjustable FPR kit made for Hondas work on the S4 fuel pressure gegulators (has 2 bolts attaching it to the rail) I would do some searching, and call AEM with stock fuel pressure specs, and measured frp dimensions, and ask them if they make any that would fit the rail. I have seen it done before, just cant find it... __________________ Rotaries:They are NOT that complicated!

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12-28-2009, 10:19 PM	#3
antman0408 Rotary Fan in Training Join Date: Jan 2009 iTrader: (1) Posts: 61 Rep Power: 16	My stock FPR crapped out after a couple thousand miles. I was getting 50 psi of fuel pressure all the time. I wouldn't worry about it until it does go bad, then replace it.