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Malpassi Making Funny Noises?

lwboosted

By lwboosted,
in Engines & Forced Induction

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lwboosted Rising Star

lwboosted

Posted
Posted

i have a malpassi running on my rb20.. its the one for when u run over 15psi boost which i am running.. but it has started making a humming noise, sort of vibrating.. it used to do this when you turn the key to ignition.. but i think it was it filling up with fuel... now it makes the noise all the time whenever i put my foot into it... any help would b good.

thanks leigh

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RB30X Rookie

RB30X

Posted
Posted

Mine used to make that noise too. They aren't designed to cop the intial wack from the fuel pump. The diaphrams inside flutter or vibrate with the pulsing of the pump. The fuel pressure gauge I installed at the same time used to bounce around crazy when it made that noise.

The way to fix this is install your old fuel regulator after the fuel rail and then the malpassi then return to tank. (I assume they are the same as RB30ET's). Hook up the vaccum lines to both. The old reg takes the punch from the pump and they both regulate pressure up to a certain psi then the malpassi takes over increasing the fuel pressure at higher boost. Everything smoothed out so much after that and also allowed me to keep a lower base fuel pressure but still run higher than standard boosting pressure to maximise fuel ecconomy.

infected flow Rising Star

infected flow

Posted
Posted
Mine used to make that noise too. They aren't designed to cop the intial wack from the fuel pump. The diaphrams inside flutter or vibrate with the pulsing of the pump. The fuel pressure gauge I installed at the same time used to bounce around crazy when it made that noise.

The way to fix this is install your old fuel regulator after the fuel rail and then the malpassi then return to tank. (I assume they are the same as RB30ET's). Hook up the vaccum lines to both. The old reg takes the punch from the pump and they both regulate pressure up to a certain psi then the malpassi takes over increasing the fuel pressure at higher boost. Everything smoothed out so much after that and also allowed me to keep a lower base fuel pressure but still run higher than standard boosting pressure to maximise fuel ecconomy.

actually malpassi pumps are very unstable i cant believe you use them when u could get a sard or bosch for the same price...

my 2c

cheers!

WilYawn Enthusiast

WilYawn

Posted
Posted
actually malpassi pumps are very unstable i cant believe you use them when u could get a sard or bosch for the same price...

my 2c

cheers!

I belive they were talking about the malpassi fpr, not the pump :P

Abo Bob Grand Master

Abo Bob

Posted
Posted

RB30X certainly seems to have a well thought and detailed answer there and I'm wondering if his solution helps out the Malpassi.

I used one for a little while but the noises and fluctuations in pressure bothered me so I sold it.

lwboosted Rising Star

lwboosted

Posted
  • Author
Posted

i am planning on putting a rb25 in my 32 so if it blows that will give me an excuse to do it.. haha

i will put the standard reg on as well and see how it goes.. but i thought that if i were to do that the pressure from the malpassi wold only hold it to the standard reg. and the standard reg would in a way block what the malpassi is doing because it becomes before the malpassi and the fuel rail.. if that makes sense...

RB30X Rookie

RB30X

Posted
Posted
i am planning on putting a rb25 in my 32 so if it blows that will give me an excuse to do it.. haha

i will put the standard reg on as well and see how it goes.. but i thought that if i were to do that the pressure from the malpassi wold only hold it to the standard reg. and the standard reg would in a way block what the malpassi is doing because it becomes before the malpassi and the fuel rail.. if that makes sense...

I know what you mean about blocking it but it will only restrict fuel flow back to the tank. Skyline fuel regs are after the fuel rail arn't they??, on the return to the tank, hence pressurising the rail.

GeeTR Grand Master

GeeTR

Posted
Posted

Hrrrm, i thought the Malpassi's where the choice, and my SARD was a jap gimmick toy i would cop shit for. This thread could prove me wrong ha.

Agreed though, the SX/Areomotive have a following. I saw dozen of units recently at the 07 SummerNats. Many injected 800hp NA big blocks

Does the fluttering actually cause regulation issues, or is it just freaking ppl out?

M

4door_Sleeper Veteran

4door_Sleeper

Posted
Posted

Malpassi dont get good press inthese forums, but I have seen them used in many top end drag cars so I doubt they are as crap as others make out.

I am aware Malpassi make a few rising rate regulators of differing specifications so one possible problem may be that people are'nt using the correct model. Mine has given me no problems, but I am only putting out 250rwkw not 1000 so I havent needed to upgrade my fuel lines etc

just my 2c

lwboosted Rising Star

lwboosted

Posted
  • Author
Posted

yeah the standard reg is on the end of the rail so fuel comes through the rail then to the reg then to the malpassi (if i put it in after the reg) then back to the fuel tank.

at the moment i have just made an adaptor in place of the standard reg..

it wierd it has only just started making the whining noise when driving lately.. it has always winded on ignition when it fills up with fuel... but it makes me thing that it is starving fuel or something?? i dont know if it is causing damage or not..

RB30X Rookie

RB30X

Posted
Posted

No damage.

4door_Sleeper do you have a fuel pressure gauge, if you did i'm sure the needle would bounce around a little bit without you noticing.

lwboosted What sort of fuel pump to you have, mine is a 500hp pump and it never made the noise until a few weeks of having the malpassi in then only makes it once in a blue moon since I installed the standard reg as well. I' almost certain is the arrangment of the rubber diaphram that causes some noise sometimes.

GeeTR Grand Master

GeeTR

Posted
Posted

Could you play with hose diameters in front of the reg, to try and remove some the oscillations out the pressure. Do they make automotive fluid "hammer dampeners" Is it possible to replace the diaphragm? All things i would check

M

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