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Re: ignition parts

To: BJ Martin <bj_martin@hotmail.com>
Subject: Re: ignition parts
From: Barry Schwartz <bschwart@pacbell.net>
Date: Fri, 25 Jun 1999 07:23:07 -0700
  < snip >
>overall; however, on a recent 300 mile trip the car stranded me on the 
>roadside twice (going and coming). The first time, it lost power and died 
>shortly after leaving a toll booth where I had to idle in oppressive heat. 
>While the temp guage didn't heat up much, I guessed that the engine bay in 
>general did and the problem was vapor lock. 
   <  snip >
>while at speed (70-75) the 
>car lost power a couple of times (did not die but would not hold speed and 
>would not accelerate) for a few moments. It then "recovered" and would run 
>strong. Again shortly after leaving the toll booth, again in oppressive 
>heat, it lost power and died. 
  < snip >
>So I am less convinced that I have a vapor lock problem. 
************************************
Your right, this is definitely, NOT caused by vapor lock.  Vapor lock is a
condition where by the fuel (when not in motion or being pumped through the
lines) is heated to the point of boiling, causing a local area IN THE
SUCTION LINE of the system to have, effectively, a large bubble in the
fluid.  Since the pump cannot pump vapor or gas (used in this verbiage to
mean not a solid or liquid) then the pump can't supply fuel to the rest of
the system, and it's like having no fuel pump at all.  The problem ONLY
occurs in the pump itself, or the inlet line going to the pump.  If there
is a "bubble" in the line AFTER the pump, the bubble is simply pushed along
with the rest of the fuel.  This is also why, if one installs a fuel pump
in the rear, very close to the tank (or in it) then as the instructions
will say, vapor lock will be eliminated.  It would normally only occur
after the fuel in said areas has been heated by the engine sitting and heat
soaking the effected areas to the point of boiling the fuel.  If the fuel
is moving (i.e. being pumped), then it doesn't stay in any one area long
enough to get that hot.  Heat soak is normally a condition that occurs
after the car has sat, not running, on a hot day, for a short time, and the
fuel has had enough time to absorb the heat that has been generated causing
the localized boiling - It sounds to me to be an electrical problem, or
possibly bad fuel, clogged filter, or even a failing pump-


Barry Schwartz (San Diego) bschwart@pacbell.net

72 FI, V6 Spitfire (daily driver)
70 GT6+ (when I don't drive the Spit)
70 Spitfire (long term project)


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