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How To: Set Up Your Fuel System


Taz_Rx

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Just had a look at that cross section of the RR FPR.

 

from the way i see it all it is, is a boost variable valve. it bleeds off excess fuel pressure via the return line. as boost increases it puts pressure against the diaphram and moves the needle closer to the seat reducing the amount of pressure being bled off and increasing the amount of output pressure.

 

I'm currently doing a machinist/ fitter and turner apprenticeship and using what i know i don't think it would be all that hard to make one from scratch. the hardest think to do is getting the boost/fuel pressure 1:1 and sealing it to stop boost and fuel leaks. I'll see if a can make one and let you know how its going.

 

CHEERS

Ryan

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Thanks taz, interesting stuff.

 

Eventually I need to sort all this stuff for the 2nd motor I build for

the KE20. I am sure this will help out.

 

Cheers,

 

Dougal

gday dudes just wanted to say about the meth/water pumps.

volvo s run a 40 psi windscreen squirter.

an they have about 3 litres hold tank,the old square ones mid 80 s.

it s hard to get a really fine spray.

the meth/water must atomize.

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  • 8 months later...

Something I was email from Wolf AEM, thought it might be slightly relavent so chucking it up here. :cool:

 

Hi Guys,

 

 

 

We all know that increasing fuel pressure means you get more fuel per squirt right?

 

 

 

Well that is mostly true.

 

 

 

The first problem is, that as we increase the fuel pressure (using an adjustable fuel pressure regulator), the extra amount of fuel coming out of the injector does not necessarily increase proportionally. And this only gets worse as you keep increasing the pressure higher, and higher. The higher you go, the less of an increase in fuel flow you are achieving.

 

 

 

The second problem is that you can end up with the fuel pressure on the back of the injector making it harder for the injector to open. This can cause idle problems. This is especially true with high impedance injectors where there is not a lot of injector opening current to overcome the fuel pressure on the back of the injector.

 

 

 

Thirdly, you can have other problems such as less efficient injector spray, and injectors leaking when the engine is not running, but there is still fuel pressure in the rail.

 

 

 

Now, this all depends on the type of injectors you are using, but the general rules apply.

 

 

 

So, what is the answer?

 

 

 

Make sure you have the correctly sized injectors to cope with the amount of power you are trying to achieve. DON'T just screw the pressure up more and more. If you are getting fuel pressure up to numbers like 55-60 PSI at idle, that may end up being a lot more by the time you are at atmospheric pressure, or even more under high boost pressure levels.

 

 

 

Maybe take some advice from someone in the industry who has experience with a project like yours. It's far better to ask and get some solid advice, than it is to go the wrong way and end up with a substandard result.

 

 

 

OK, that's it for now.

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  • 5 weeks later...

how would the car go if u did not have return line & FPR plumbed in?

 

would the system rely on reliable fuel pump that supplies a constant pressure?

 

 

just throwing this in the air cos I'm wondering what to do with my blow through 4k,

 

my carby does not have a return outlet plumbed in. and with the turbo setup on it never had a return line pulmbed

 

 

 

the other option that i had considered is putting a T piece in the fuel feed, and running that into the FPR.

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how would the car go if u did not have return line & FPR plumbed in?

 

would the system rely on reliable fuel pump that supplies a constant pressure?

 

 

just throwing this in the air cos I'm wondering what to do with my blow through 4k,

 

my carby does not have a return outlet plumbed in. and with the turbo setup on it never had a return line pulmbed

 

 

 

the other option that i had considered is putting a T piece in the fuel feed, and running that into the FPR.

 

 

I used to have a very basic fuel setup. Consisted of a Carter BLACK pump (100gph and 14-16psi) - which had about 12psi in the engine bay, and NO REG AT ALL! This gave me a potential of aboput 10psi of boost (keeping a 2psi fuel presure buffer). HOWEVER - It was only possible because the needle and seat in the weber I was using could hold the 12pis at idle.

If you tried to do it with a stock carb the pressure would bust open the needle and seat and turn you carby into a fuel fountain.

 

If you use a proper carby turbo rising rate reg then it actually works on the send line, not the return like an EFI setup.

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  • 9 months later...

just one thing relating to this thread, on my ae71, ive got three fuel lines running underneath the car, now i know one is pressure line and the other line is return, what do i do with the thirs, i think it relates to the charcoal canister but do i need to use that (I'm doing a 4AGE conversion)

 

Cheers

 

Prewer

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You're modifying your tank somehow at the moment aren't you mate?

How many line to you have coming out of the tank?

 

Should be no issue with removing the line all together and blocking the tank end, or just block it off in the engine bay. Depends how neat you want things I suppose.

 

...oh and yeah it would be from the charcoal canister. :P

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