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Re: Carb Leaking

To: spridgets <spridgets@autox.team.net>
Subject: Re: Carb Leaking
From: Bob Spidell <bspidell@comcast.net>
Date: Fri, 16 Feb 2007 08:07:18 -0800
Hi David,


I gave this some thought (for once ;) and must respectfully--and 
mildly--disagree.

For the last 15 years or so I have taken an extended trip in my BJ8 
throughout the western
US, Canada and Mexico.  We are, at times, literally 100 miles from 
nowhere and out
of cellphone coverage.   Obviously, reliability is a big concern (along 
with carrying the
right spares and tools).  One recurring problem--at least until the last 
few years since
I installed a solid-state SU pump--has been with the fuel pump.  Every 
morning before I
start the car I turn the key to the "run" position and listen to the 
pump come to life.  Usually,
I get one or two clicks and sometimes I get none, which is worrisome 
until I get a start
and smooth running.  This reassures me that the fuel system is tight and 
sound and I'm good
to cross that 100 miles of Nevada desert (well, at least I have a 
fighting chance).

If I were to get a bunch of clicks--absent extenuating circumstances 
like ambient heat--I
would not hit the road until I've found the cause of the problem.  This 
has, in fact, happened
a couple of times.  Usually, it means snugging the banjo bolts on the 
carbs and fuel pump
(checking these is now part of my pre-trip inspection--like I said they 
can work loose). 

If you always got a bunch of clicks before starting how would you know 
when you have
a problem?

The check valves in the pump are, shall we say, butt-simple.  They're a 
flexible, fuel-proof
plastic flapper valve with a metal ring and a "keeper" tab.  If one 
isn't working properly it's
either not installed correctly, damaged or there is some crud where the 
flapper should seat. 
I wouldn't launch with any of these problems. 

And, not to be disrespectful, but the outlet check valve won't retain 
pressure anyway--it's
meant to allow flow TO the carbs (but not backflow).  It's the inlet 
valve that should close
and allow the pump diaphragm and the float valves to retain pressure 
(even overnight). 
Like I said in my earlier post, if your pump is clicking madly you 
probably have a leak on
the inlet side (or a problem with the inlet valve--not likely).

FWIW, as anal as I am about this I've never run with a fuel 
filter--besides the thimble-sized
screens in the carbs and the screens in the pump--and never had a 
problem with fuel
contamination.  I installed a new tank years ago and sloshed it with 
some sort of coating
which appears to have held up, so far.  I also installed Grose jets many 
years ago--when
they were good--and have never had a problem with flooding.

Unless you add other gauges (oil temp., vacuum, amp, etc.) the safety 
gauge and your
ears, nose and eyes provide the only clues as to how things are faring 
in your car. Being
the only car 100 miles from nowhere really sharpens the senses.


bs



DavidNLonsdale@aol.com wrote:
> Hi,
>  
> The fact that the pump is ticking does not necessarily mean that the carb  
> (ie. float valves) are leaking. It just means that the pressure in the fuel 
>line 
>  is decaying. The most likely cause is the pump outlet valve not fully 
> seating.  It's not really a problem and I wouldn't worry about it.  
>
> Regards,
>
> David Lonsdale
> Cirencester,  UK
>
>   
***************************************************************
Bob Spidell         San Jose, CA        bspidell@comcast.net
'67 Austin-Healey 3000             '56 Austin-Healey 100M
***************************************************************




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