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Re: Fuel Lines & Fuel Pressure

To: "Brucciani, Chris" <CBrucciani@archinsurance.com>,
Subject: Re: Fuel Lines & Fuel Pressure
From: Perry Smith <tpsmithstl@yahoo.com>
Date: Fri, 30 Sep 2005 07:59:20 -0700 (PDT)
Absolutely!  Basic Fluid dynamics, if you open the aperture wider (smaller to 
larger fuel hose), pressure drops.  The relationship is inverse to pi-r-squared 
(area or opening), in square inches (or square mm, whichever you measure).  I 
think the pressure at the carbs (on my SU's) has to be about 4psi. (3-6psi 
range, off the top of my head, but according to the manual)  I recently put a 
manual pressure regulator on them to ensure I wasnt over-pressuring the float 
bowls a higher RPM's.

 

BTW, you'll also get a minor (but probably imperceptible) drop across the fuel 
filter.

 

Perry Smith

'68 2000


"Brucciani, Chris" <CBrucciani@archinsurance.com> wrote:
Thanks to fellow listers Pinky's electrical gremlin has been calmed (for now).
I have a hunch that I may be lacking fuel pressure at the carbs. I have an
electric fuel pump located on the frame. It feeds into an inline gas filter -
out to about a 5/8" fuel line - into another inline filter (I need to remove
this but before I changed the hard fuel lines and coated the gas tank I had a
lot of rust) then into a =" or so fuel line to the carbs. It doesn't appear
that I get good flow to the second filter. Would a too large fuel hose
contribute to a lack of fuel pressure?

Chris Brucciani
Marietta, GA
1968 2000 "Pinky"
1973 240Z


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