newbee

i am having a fuel pressure regulator put on my 7 tommorrow and i don't know how much pressure to tell the guy to put it at are around. would really help if you could tell me what you run. Thanks in advance

maxcooper

Unless you plan to re-tune, run a base pressure (manifold reference hose disconnected while adjusting) of about 38 psi. Changing the fuel pressure will change your mixture, so you'll want to re-tune the car if you change it.

-Max

Wargasm

Max is correct. If you are just adding the regulator but making no other changes, leave the pressure exactly the same as it is now. I believe that the stock RX-7 has 38 PSI fuel pressure at 0 manifold pressure.

I run mine a little lower... at 36 PSI fuel pressure at 0 manifold pressure. You should be using a 1:1 boost compensating regulator.

newbee

thanks guys that helps alot

toylee

iTrader: (2)

can anyone explain me. what does mean at 0 manifold pressure?? thanks.

poss

iTrader: (5)

Vacuum hose connects from the intake manifold to the regulator. When you are on boost, say 10psi, it'll raise by the amount of boost you are running, an equal 10psi. This is assuming a 1:1 regulator. When you are on boost the injectors have to "fight" that extra 10 psi to inject the same amount of fuel.

Does that make sense? So at 0 manifold pressure, that is refered to as base pressure because fuel pressure changes depending on boost.

jasonlel

Do you guys mean 38psi at idle? I thought it is about 31-32 psi....

Please advice...

HDP

iTrader: (2)

At idle the engine draws vacuum so it would require less fuel pressure to maintain the same amount of fuel than at 0 manifold pressure (equal amount of boost pressure and vacuum)...

GARCO MOTORWORKS

HDP is correct so to adjust start the car and warm up .When warm pull the vacuum tube from the FPR and plug the hose .Set the fuel pressure to 38 lbs [ I use 40 psi ] ,then reconnect the hose . The vacuum should pull the pressure down to about 32 34 lbs . At boost the pressure will go above 40 psi at the rate of 1 psi boost per 1 psi fuel pressure .

jasonlel

Initially I'm running 24psi at idle, after I have install a walbro fuel pump, I'm getting 30/31psi on idle.

But I'm still experiencing jerks during positive boost. (maybe around 0.1-0.3) I'm very sure is not the ON boost jerk coz it jerk a few times. What could be the reason? Fuel filter just change few mths back.

Some extra information
Exhaust temp, degree celsius
On idle: 400
Normal driving:500-600
Hard Drive:>600 ~ <650

t-von

iTrader: (8)

Good thread. So if I was to install a Walbro fuel pump on my stock car with no other mods (for preperation for future mods). Would I have to adjust the FPR for the increased fuel flow?

jasonlel

On the other hand, could it be the fuel pump not getting enough voltage?

HDP

iTrader: (2)

The stock FPR is not adjustable...

jasonlel

At last, my problem solved.

Did a check at fuel pump wiring voltage. Everything is oke. Last resort was to look at the fuel pump resistor. We are not sure how to check if the resistor is in perfect working condition, so we switch to another resistor. But it didn't solve the problem. So out of curiosity, I did a voltage check on the wire connecting to the resistor. I'm getting about 10v+/-. So I guess this is the culprit. It is not powering enought voltage to the fuel pump resistor.

So I by pass the fuel pump resistor and rewire the fuel pump to get 12v from batt source with a relay.

Violaaaaa, problem solved!!!!

*Solving this problem, I too solved another problem at the same time. See link ->
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/bad-idle-during-turbo-timer-shut-down-505061/

t-von

iTrader: (8)

I know that! I quess I should have been more specific. Would I need to buy a new FPR to re-adjust the fuel pressure with the higher flowing pump?

maxcooper

No. The FPR would not be doing a very good job of regulating pressure if it changed a lot at different flow levels.

It is possible to overwhelm the regulator by running a monster pump at boosted voltage with a pinched return line. But just installing a pump isn't going to mess up the fuel pressure.

-Max

GoRacer

iTrader: (2)

I have mine set to 40psi vacuum unpluged but mine drops to 36psi with vacuum. I orginaly thought people were setting 40psi pluged base pressure.

NAN777

i have a question here..... i'm running ULTRA rich... like saying air fuel ratio of 8 on high boost . and idle at 11..... basically pretty stock... except the remapped ECU...

is it possible my stock fuel regulator is screwed and my pressure is in full power causing the fuel to be that rich ?

HDP

iTrader: (2)

Back from the dead... pulling the vacuum hose at idle is this the only way to adjust fuel pressure? The location I have my FPR mounted, it is nearly impossible to remove the vacuum hose without disassembling stuff which I can not do while the car is running. Is there any other way?

HDP

iTrader: (2)

^^ Anyone?

arghx

iTrader: (3)

On my FC, there is a test connector that lets supply you ground the circuit opening relay to pressurize the fuel system with the engine off (to check for leaks). I just used that and set it to 40psi. I'm not so sure how you could do the same thing on an FD.

Banzai-Racing

iTrader: (11)

In the diagnostics box jumper the f/p (fuel pump) and gnd (ground) this will keep the fuel pump running.

GARCO MOTORWORKS

HDP =just pinch the hose closed with some type clamp . Test oan set the adjustment at 40psi .