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Re: too much fuel pressure?

To: Spitfires@autox.team.net
Subject: Re: too much fuel pressure?
From: Marv Coulthard <coulthard@saltspring.com>
Date: Thu, 30 Oct 2003 23:10:06 -0800
At 01:22 PM 30/10/03, you wrote:

>In my last post, I explained that my stock ZS carb had given up the ghost, 
>and 3 rebuilds had not been able to resolve the main problem - that of raw 
>fuel overflowing from the carb vent after a few minutes of running.
>
>I replaced the carb with a new Webber DGV 32/36 and was amazed that it 
>started and ran quite well - for a few minutes.  While waiting for the 
>engine to reach full operating temp, I observed that raw fuel began to 
>drip from the secondary, and then the primary.  Once it started the car 
>began to belch and cough.
>
>I have a mechanical pump - one I paid a little extra for back in April.  3 
>rebuilds and now a new carb is having a similar problem.  Oddly, I've put 
>several thousand miles on the fuel pump and old carb before this started.
>Could the pump have suddenly begun putting out a higher pressure? or am I 
>simply incapable of checking a float height correctly


Drop a fuel pressure regulator in line.   This is a really common 
problem.  I had it on my Morgan also on my wifes Spit.  SU's like about 3 
lbs pressure.  In the Morgan I found the old electric fuel pump all of a 
sudden puting out 11-12 lbs.  then 1000 miles later gave out.  Fuel 
regulator did the trick so it stays in line.   The electric pump has two 
advantages.  It keep working at a constant speed no matter what revs... and 
... it will fill the float bolls before you start.  This is an advantage 
for starts after a while of sitting where the level can drop in the floats 
due to evaporation.  The regulator keep the pressure constant no matter 
what the speed of the engine.

cheers
Marv




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