# Adapting pressure regulator for carbs to CIS fuel system.



## Tom A (Oct 20, 2004)

Planning on installing side drafts on to my A1 GTI race car, and would like to use a pressure regulator with the stock CIS fuel delivery system. I can get a return type regulator with guage, but am having a hard time coming up with a way to connect to the factory lines. The supply line appears to be a 14mm Bubble flare connection, is that correct? I am not worried about the return line, the factory return line is a barbed fitting, and I should be able to reuse it, as the return is low pressure. The supply side will be pretty high though, ~70 PSI.
Anyone done this? Any ideas, hints, lessons learned?
Thanks,


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## VWralley (Mar 30, 2002)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*

i would highly advise against it. i did this on one of my first motor swaps with in my rabbit. i constantly had fuel issues with lines breaking and leaks and all that...on top of that the cis pump has a pulse that kinda messed with the runabilty of the carb
get yourself a carter 4090 i think is the model, i used one of those with no regulator and it worked awesome


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## Tom A (Oct 20, 2004)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (VWralley)*

I am on the fence with this one. 
On the plus side, the stock fuel system is pretty robust, well protected, is already there, and we have spares for it. There are a lot of people using a similar system in Porsche 911 race cars, 73.5 to 83 cars had CIS, and switching to Webers is a common change. The regulator I am looking at is less expensive than a new fuel system.
On the down side there is a higher possibility of leaks with a high pressure system, and having high pressure fuel when it is not necessary bugs me.
If I run a low pressure pump with regulator, I doubt I can use the existing hard lines, and it may not fit as elegantly as the stock pump.
If I can't find the proper fitting, it may not even matter.


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## WackyWabbitRacer (Apr 24, 2001)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*

I also suggest the usage of a Carter 4070 low pressure fuel pump. IIRC the Carter has a maximum fuel pressure of about 6 psi, and you can use standard "gas rated" rubber/steel lines for the connections.
I used Aeroquip steel braided fuel lines (AN #4) in my old SCCA Rabbit.
The problem with using the CIS fuel pump is the amount of pressure it creates, about 100 psi deadheaded which is difficult to regulate for a carb application.
The Carter fuel pump is relatively inexpensive and very reliable.
Cheers, WWR.


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## antichristonwheels (Jun 14, 2001)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*

you have almost 80psi for a set of carbs that need <4psi. get a more suitable pump and regulator, and a guage.


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## Tom A (Oct 20, 2004)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (antichristonwheels)*

Thanks for the advice.
Just to clarify, the regulator I am looking to use is specificly designed to run carbs with a CIS fuel pump. It is made by PMO carburators, who makes a modern improved version of Weber 40 and 46 IDA carbs for Posche 911s. It is a recurculating regulator, with the excess fuel going back to the tank using the stock CIS return line. PMO is widely regarded as the best carbs to put on an air-cooled 911, and the fuel system that PMO reccomends for CIS cars is their purpose built regulator. PMO carb kits sell for about $3,000, so if they thought a different fuel pump was better, they could sell them easily. Instead he sells a regulator, with built in pressure guage for $50.

The install base for these systems is quite large, and I know several people running these systems on track and race cars for years with no problems at all. I have no doubt that it will work fine if, and this is a big IF, I can adapt it to the supply and return lines, as VW used different fittings that Porsche did, and so far I am having little luck finding the correct fittings.
This is the unit:


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## antichristonwheels (Jun 14, 2001)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*

dude
I take back what I said. That looks like a great solution. I'm gonna get one for my Caddy project. Very cool item.


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## gourmandster (Aug 13, 2006)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (antichristonwheels)*

PMO's are sweet, If I was going to convert my 911 over to carbs that's the way i would go.


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## 16vDigiGti (Aug 23, 2005)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*


_Quote, originally posted by *Tom A* »_Thanks for the advice.
Just to clarify, the regulator I am looking to use is specificly designed to run carbs with a CIS fuel pump. It is made by PMO carburators, who makes a modern improved version of Weber 40 and 46 IDA carbs for Posche 911s. It is a recurculating regulator, with the excess fuel going back to the tank using the stock CIS return line. PMO is widely regarded as the best carbs to put on an air-cooled 911, and the fuel system that PMO reccomends for CIS cars is their purpose built regulator. PMO carb kits sell for about $3,000, so if they thought a different fuel pump was better, they could sell them easily. Instead he sells a regulator, with built in pressure guage for $50.

The install base for these systems is quite large, and I know several people running these systems on track and race cars for years with no problems at all. I have no doubt that it will work fine if, and this is a big IF, I can adapt it to the supply and return lines, as VW used different fittings that Porsche did, and so far I am having little luck finding the correct fittings.
This is the unit:


















why worry about fittings? the regulator has barb fittings on it. just get some high pressure fuel hose and problem solved.


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## Tom A (Oct 20, 2004)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (16vDigiGti)*


_Quote, originally posted by *16vDigiGti* »_why worry about fittings? the regulator has barb fittings on it. just get some high pressure fuel hose and problem solved.
The regulator is availaible with different fittings, Barbed, AN, and I believe NPT. The problem is not the regulator end anyway, it is the hard supply line from the pump.
Not sure I trust a barbed fitting and hose clamps for that high a pressure.
My first choice would be to have a single line from the hard line to the regulator, but that is looking difficult, as I can't find the correct fitting to the hard line. My next option is to see if I can use the stock line and use the banjo bolt that screws in to the fuel filter. That should be a stock metric fitting. Each joint is a possible leak, but I would rather have several joints on a high pressure line that a barb and hose clamp.


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## chrisbmx68 (Aug 14, 2003)

not exactly what your looking for, but I have high pressure fuel hose pushed over the plain hardline for cis with a nice hose clamp and it works fine no leaks. I just cut off the fittings and did it that way to convert to efi


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## VWralley (Mar 30, 2002)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*


_Quote, originally posted by *Tom A* »_Not sure I trust a barbed fitting and hose clamps for that high a pressure.


get the -6an fitting and use Jegs brand Push-loc hose and fittings. they are rated for over 240psi and are easy to install and come it like 6 colors, check em out. i use them on every standalone install i do, never once had an issue.


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## vee_dubb_gti (Nov 17, 2004)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Tom A)*


_Quote, originally posted by *Tom A* »_



















WOW







if it works http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## wilburisthecoolest (Jan 13, 2008)

I just cut the fuel lines after the last body holddown clip. Found some fuel line (3/8 high pressure i believe) and clamped it down
I also used a tee fitting from home depot for the return line before the cheapy $20 fuel regulator from Autozone to get fuel pressure down to 2.5 psi. Even bought the $12 fuel pressure gague.
Total spent was $47 for everything, clamps, fuel lines, everything. I kept the stock pump and filter.
dont knock it. Its simple, easy, cheap, and most of all, it works. The less you have going on the less you have to break.
Remeber the motto.. K.I.S.S. Keep It Simple Stupid.


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## iceman2.0 (Mar 28, 2006)

*Re: (wilburisthecoolest)*

This system should work for just one carb too right?


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## VenaGTi (Mar 19, 2006)

*Re: (iceman2.0)*

i wonder if that gizmo costs more then the 4070 pump? i didn't see a price on the pmo web site. 
another consideration is placement of that jammy. if it's in the engine bay, i suspect you are just constantly circulating the gas from your tank to a hot engine compartment and back at a very high rate of volume. will the entire contents of the tank will heat up higher then just a non return system? is this good, bad or ugly?


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## antichristonwheels (Jun 14, 2001)

*Re: (VenaGTi)*

mine was about $65-70 delivered with a pair of filters


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## psykokid (Apr 2, 2002)

*Re: (antichristonwheels)*

you can take the stock CIS line and cut the crimped hose end fitting off and you get a hose barb of the appropriate size. I had a CIS line leak and in a pinch i cut off the old fitting and got some standard EFI hose and used two EFI hose clamps..


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## iceman2.0 (Mar 28, 2006)

*Re: (antichristonwheels)*


_Quote, originally posted by *antichristonwheels* »_mine was about $65-70 delivered with a pair of filters

did you remove the accumulator? Can you block one of the fuel outlet fittings for just one carb? If thats the case im buying one.


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## Anthony077 (Feb 17, 2008)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (VWralley)*

hi i saw that you mentioned that you used jegs brand push loc line for fuel lines. i had ordered this for my mk2 project and i saw that jegs states its not recommended for fuel line use just wondering if i should return it or use. How did it work out for you?


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## iceman2.0 (Mar 28, 2006)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (Anthony077)*

http://****************.com/smile/emthup.gif


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## iceman2.0 (Mar 28, 2006)

*Re: Adapting pressure regulator for carbs to CIS fuel system. (iceman2.0)*


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## 2L Bunny (Aug 15, 2000)

Easy way to do it.
Buy one of these:
http://www.cbperformance.com/c...D=577
Put it where your CIS pump goes, also pull the acumulator out and use the existing hardline to run fuel to the engine bay. No need to pump excess fuel into a hot engine bay.


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## B4S (Apr 16, 2003)

*FV-QR*

I second that idea. I'm running a 2.5-4.5psi Facet 40105 pump, without a regulator, and it's the best thing I ever did for my car. I've been tempted to snag that CB pump, but I already did away with all my stock pump mounting points







.


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## wantacad (Apr 4, 2003)

*Re: FV-QR (B4S)*

nice


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