# Can you ByPass the Wam Up Regulator?



## sflamm (Mar 23, 2007)

is there a way you can by pass the warm up regulator - and just us a fuel pressure regulator?
if so, is there any pros or cons?


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## The_Hamster (Jul 31, 2000)

*Re: Can you ByPass the Wam Up Regulator? (sflamm)*

Sure can.
Pro is that you have more control of the warm up operating, and the final control pressure.
Con is that *you* have to maintain control of the warm up operating, and the final control pressure.


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## sflamm (Mar 23, 2007)

*Re: Can you ByPass the Wam Up Regulator? (The_Hamster)*

so, i still have to use the warm up regulator?
i cant just totally bypass it - and just run a fuel pressure regulator?
do you have a picture or diagram of the set up ?


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## The_Hamster (Jul 31, 2000)

*Re: Can you ByPass the Wam Up Regulator? (sflamm)*

No you don't HAVE to use the WUR, but if you use a fuel pressure regulator it has to be an adjustable one that you keep track of as the car warms up. The control pressure needs to be lower with a cold engine, and higher with a hot engine. Some guys use a manual one on a race car, but on a street car it would be totally impractical.
Ask WackyWabbitRacer, he had a manual setup on his Rabbit Racecar IIRC...


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## antichristonwheels (Jun 14, 2001)

*Re: Can you ByPass the Wam Up Regulator? (sflamm)*

don't


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## sflamm (Mar 23, 2007)

*Re: Can you ByPass the Wam Up Regulator? (antichristonwheels)*

why?


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## mittimj (Dec 27, 2006)

*Re: Can you ByPass the Wam Up Regulator? (sflamm)*

I have heard of it being done on street cars plenty.


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## sflamm (Mar 23, 2007)

*Re: Can you ByPass the Wam Up Regulator? (mittimj)*

well - before i became a vw fan - i had a honda and used a fuel pressure regulator - but, with the cis engines its a totally new ballgame - and everything works with each other in some way.
I want to see if anyone has either bypass it totally or can you incorporate it with the wur


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## WackyWabbitRacer (Apr 24, 2001)

*Re: Can you ByPass the Wam Up Regulator? (sflamm)*

The Control Pressure Regulator (aka CPR, WUR) is basically a variable hydraulic choke that changes the amount of Control Pressure to the top of the control plunger inside the fuel distributor.
On a cold start, the amount of Control Pressure is lower for an initial richer fuel mixture. As the engine warms up and the bimetallic strip inside the CPR is heated, the amount of Control Pressure increases to about 58 psi for the correct fuel mixture and lower emissions.
Yes, the CPR could be interchanged for a fixed fuel pressure regulator. However cold start difficulties could result depending on your winter climate.
I modified a CPR to make it manually adjustable so I could set a lower "hot" Control Pressure for a richer fuel mixture on my old WackyWabbit SCCA H-Production road racer. 
In the early spring of the year, I would have to insert a dime between the throttle stop and the throttle linkage to get the engine to idle on a cold start since the Control Pressure was too high for a cold start since the pressure was fixed.
Cheers, WWR.


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