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Location:
qld
Registered:
May 2003
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fuel pressure regulater
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Sat, 20 December 2003 09:40
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im buying an inlet efi manifold for my 2tg it is a custom made manifold and has a custom fuel rail thought is does not have a fuel pressure regulater not quite sure the total use of these but will i need one when puttin it on my car,
jason
i will be setting the car up with pre pump surge tank and efi tank incase this info helps.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: fuel pressure regulater
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Sat, 20 December 2003 11:25
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you really need to know what you are doing with an EFI install... if you understand why thingd are there, you're less likely to hook shit up backwards 
the fuel pressure regulator does just that. it regulates the pressure of the fuel.
in practice, the fuel pump is effectively a positive displacement pump, so it puts out a constant volume of fuel. in order for the fuel rail pressure to be constant, you need to bleed off excess fuel to stay at the desired pressure. this is what the fuel pressure regulator does..
keep in mind that at idle, the engine is using buggerall fuel, so almost ALL of the pumped fuel is being returned!!!
you can just get an external pressure regulator. either a stock one (i have an external from a VL if you need one), or you can go for a fancy external one like a Malpassi or similar.
alternatively you can get the fuel rail tapped to accept a threaded one...
much easier to have an external one tho you can put it before or after the fuel rail. there are some reasons to put it after, but it really won't matter that much.
Cya, Stewart
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Location:
qld
Registered:
May 2003
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Re: fuel pressure regulater
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Sat, 20 December 2003 12:46
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thanks for the help ill have to let you know about the vl fuel regulator after i buy what im buying and if i get it. efi is slowly making more and more sence, what do you think about it on a 2tg over twin sidedrafts, just your personal opinoiun.
thanks alot. jason
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: fuel pressure regulater
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Sun, 21 December 2003 16:27
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How does a fuel pressure regulator work in front of the fuel rail?
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: fuel pressure regulater
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Mon, 22 December 2003 03:43
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theoretically a fuel pressure reg will work anywhere in the system. the function is to keep the pressure AFTER the fuel pump at a given amount. frinstance, the 'returnless' pumps in newer cars DO NOT have a pressure regulator, and so do not have recirculating fuel at all!!!! the pump determines the pressure supplied, and the fuel goes from pump to injectors and never ses the tank again.
in older systems, the fuel is circulated thru the regulator to keep the pressure constant by bleeding off fuel volume.
you could have the regulator just after the pump if you wanted to.
the only reason to have it after the fuel rail is so that fresh fuel passes thru the rail all the time to keep it cool, and so that if you mash the pedal and a large amount of fuel suddenly leaves the rail vis the injectors, there is less of a hsitation before the pressure returns to normal.
in practice i don't think that is that much of a concern.
i would be happy to run a regulator before the rail and cap the end of the rail off...
then again, for aussie conditions, having fuel always passing thru the rail to keep it cooler might help prevent heat soak and any vapourisation probs...
hmmm. i guess it also helps if you have it at the end so as to be able to pass air thru it.... if there is air/vapour in the rail, and the reg is before, then the air will hav to leave by the injectors, whereas if reg is after, the pump will force the air out of the rail....
a few thoughts
Cya, Stewart
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