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Re: [T3] fuel pump problem


On 25 Jul 2004 at 21:03, Keith Park wrote:

> If the pump has a different flow rate, or can produce more or less
> pressure... wouldnt that change the orifice size needed to keep the
> pressure at 30? 

Increasing the pressure/flow in the regulator has the effect of increasing the 
orifice size, just by virtue of the movement of the diaphram. The change in 
pressure would be dependent on the spring constant of the spring behind the 
diaphram. I think that spring's pretty long compared to its range of motion in 
use, so I'm guessing that the pressure wouldn't vary much.

For comparison, consider what happens when our FI engines use lots vs. little 
fuel. The flow thru the regulator changes in response to this, but we can't see 
any change in pressure.

Of course at some point the whole regulator could be overwhelmed due to the 
size of it's central pipe, but at that point adjusting the screw won't make any 
difference any more.

-- 
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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