davidykhor

i replaced a GSS342 into my car but now i am having pressure problems.

the fuel pump pressure of the 255lph is too high or something, from inside the car,i hear the pump sound pumping. and when i rev the car from standstill, the car sounds like


vroom vroo vroo vroo vroommm

but when the car moves above 4000rpm -> redline everyting is fine

anyone can help me ?

dannobre

iTrader: (3)

Check the fuel pressure

Are you using the stock FPR?

staticlag

Mine does the same thing. Others have reported this pump is noisy as well. Though it couldn't hurt to check the fuel pressure.

D

YaXMaNGTO

Yep. I helped install 255lph in my buddy's TT GTO. That sucker is loud...
You didn't wire it up wrong, did you?

davidykhor

Only 2 wires lolx ..

The Fuel Pressure is too strong ...

Also i have a meter checking the Voltage for the fuel pump, its variable, as in it goes up and down depending on speed.

dannobre

iTrader: (3)

Did you hook it back up the same way as stock?

davidykhor

THe Stock socket was direct plug in to the walbro.

Arrrrex-8

I've got a 255lph walbro on my eagle talon. I'm sure it is a different model than what you used on your RX8, but it is very loud. This is common with walbro's, I've heard them referred to as whinebro's many times.

davidykhor

The problem now is not the sound

i don't mind the sound.

the problem now is the pressure from the walbro is too strong and somehow making the car low-end bad and sort of overfueled or something.

dannobre

iTrader: (3)

I was thinking about the plumbing more than the wiring

olddragger

iTrader: (3)

walbro pump does not work well with a pulse width modulation signal our pcm sends the pump. I have been searching for a replacement myself. Havent found one yet that doesnt require rewiring. And if you do that-- there is all kinds of things to think about.
Put stock pump back in.
OD

MazdaManiac

iTrader: (3)

You need to use a return fuel rail and an external pressure regulator with a higher flow pump like that.

The dead-end rail that comes with the car will suffer from some pretty erratic pressure fluctuations as you have it set up now.

davidykhor

yeah

since the car will be having a 13b-re swap in soon, i rather keep it as it is ...

olddragger

iTrader: (3)

THAT is a horse of a different color!
OD

04RX8man

it sound like too high of pressure

ajsabido

Hey, i was actually considering purchasing a walbro 255lph HP, and decided to do some research before hand and found this thread. My pump in my car is going out i believe ( 2004 rx8 MT, 106k miles, stock pump, 2.5mm wires, k&n drop in, AP mid pipe, ES Catback R-II Titan) I was having some problems at my mid power range and was told to do the pump swap. but if this pump is gonna over fuel my 8 than theres a problem lol...i want to fix the problem i have not make it worse. someone please clear my state of mind cuz i was loving the idea of the pump upgrade!

dannobre

iTrader: (3)

The pressure regulator if it is working properly will not allow the pressure to rise past what the regulator is set at...so you can basically put in almost any pump and be OK.

You might want to look at the Aeromotive pump or the Deutchwerks units instead...quieter and better quality

ajsabido

What would you recommend for just a hassle free swap that can give me better performance without much modifications. if that exist from reading above the rx8 doesnt like higher fuel pressure?

edit: sorry didnt fully read your post, is this pressure regulator something that could be causing my problem of low power in low and mid rpm range rather than the pump itself?

dannobre

iTrader: (3)

The regulator is part of the stock fuel pump unit...it is very simple and likely isn't your problem

How many miles on your pump assembly? If you are over 100K you might as well buy a new OEM one...cause the filter will likely be getting plugged up by then and it also is integrated into the pump assembly

jay_tibo

Yep dannobre is right, but when you do the Walbro swap you have to change the filter for the one the fits the pump (also my pump had 130,000km and the filter looked fine). It took me all of an hour, a dremel, a box of donuts to bribe the Mazda dealer into leading me the special tool, and one beer to instal the pump that cost me 100$, it buzzes a little but not a big deal.

Only way to know if your fuel pump is causing this issue is to test the fuel pressure at the problematic rev range. Don't just throw parts at the car figure out whats wrong first. How's your cat? Although this would show more at higher rpm's how old are the coils and plugs? Has this motor been compression tested? Any codes from the computer? Make sure the intake manifold valves move freely for the full motion, if they don't and are allowing to much air it will bog out the motor. How much loss in power are we talking about, is it constant or intermittent? is it the seat of your pants feeling?

I would make sure all the maintenance and wear items are tip top then see were you stand.

Cheers