RE: [DML] Re: Warm Start Issue -- Looking Elsewhere Than Fuel System (David McKeen)

["John Hervey" <john@xxxxxxxxxxxxxxxx>]

Ok, 
Set the template for what is what. 
Hot Start ( a relative term ) to me is any where above the 95F where the TTS
switch contacts has open and will no longer activate the cold start valve.
So with a bad accumulator the car has a hard time starting.
That can just be a quick trip to the 7-11.
John Hervey



-----Original Message-----
From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of
Peter Lucas
Sent: Sunday, February 10, 2008 2:21 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: Re: [DML] Re: Warm Start Issue -- Looking Elsewhere Than Fuel
System (David McKeen)


On Feb 10, 2008, at 9:30 AM, Harold McElraft wrote:

> I think it is a pressure problem. Your symptom description seems to
> confirm it.

I don't mean to be snippy, but you guys just aren't listening.  If you  
search the archives, you will see that there have been many reports  
over the years of a "warm start" problem.  This is different from the  
classic "hot start" problem, which is indeed usually caused by a bad  
accumulator.

Hot Start Problem:
This happens when the engine is hot. Like when you stop at the gas  
station, fill the tank, and then are embarrassed because you can't get  
the car restarted.   As Farrar's quotes from the service manual make  
clear, this is caused by a very hot engine causing fuel to vaporize in  
the system:

> "The accumulator maintains pressure in the fuel system to prevent fuel
> vaporization while the vehicle is not in use." --Tech manual, pages
> 46-47."

Whether you want to call this "vapor lock" or not doesn't matter, it  
is heat-induced vaporization that causes "hot start" problems.


Warm Start Problem:
This occurs after the car has been sitting for several hours. This is  
far longer than the specified minimum hold time for rest pressure--by  
this point, the engine is assumed to be cool enough not to cause the  
kind of vaporization that the accumulator is intended to prevent.   
However, it is still warm enough that the cold-start valve is  
inoperative. Something causes this problem, and it can't be the  
accumulator (because according to spec, there isn't expected to be  
rest pressure after several hours).

Many of us have been plagued by this problem, and I do not believe  
that a definitive explanation has ever been forthcoming. (I am the  
author of the article in the Tech Section on installing a full time  
pressure sender -- http://www.dmcnews.com/Techsection/fuelpressend.htm  
-- so I know how my fuel system behaves).  It is true that swapping  
the plugs will solve both a Hot Start and a Warm Start problem, but  
this does not make them the same thing.

Given that there have been several reports of the Warm Start Problem  
beginning after a water pump swap or other major engine procedure, my  
guess is that it is due to an accumulation of small problems, such as  
vacuum leaks, improperly gapped spark plugs, etc.   But that is just  
speculation--sure would be nice to nail a definitive explanation.     
But blindly blaming the accumulator won't get us there.


--Pete Lucas
   VIN #06703


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