[DML] Re: Question for owners with issues.

["therealdmcvegas" <dmcvegas@xxxxxxxxx>]

So it would seem that the point of my post was lost. It was an effort
to empower you by giving you direction to resolve this issue, not a
personal attack. And at that, it wasn't directed at you specificly either.

First off, the outside temperature certainly is germane to the issue.
Open up you Workshop Manual, and turn to page D:01:15, 2nd colum,
bottom paragraph:

"The car is wired for a hot start relay. This relay can be installed
if a hot starting problem is experienced in excessively hot regions of
the country. When this relay is used, the cold start valve will inject
intermittently durring cranking, when the engine is hot."

Since I failed to properly communicate my words previously, let me
explain my side of the story here as to why this is not a *design
flaw* as you believe, and is a problem with a failed component of your
fuel system, utilizing factual systems theories to back up my
statements. Most importantly here, since others are having this same
issue, this message is addressed to them as well. This will also help
them to understand issues with their own cars as well.

Fact #1: When cold, the K-Jetronic system utilizes a 7th EFI-type Cold
Start Injector to spray extra fuel into the combustion chambers in
order to cause a "choke" condition on the engine (cold combustion
chambers will cause atomized fuel to condensate, and have a lower
flashpoint).

Fact #2: The K-Jetronic fuel injection system CIS type that relies on
high fuel pressures to force spring loaded valves to crack open on the
fuel injectors to deliver fuel. In addition, the fuel pressures
themselves are used to meter the amount of fuel dispensed from the
injectors themselves.

Fact #3: When at rest, the K-Jetronic system relies upon a series of
check valves to maintain rest pressure of the fuel system. This
ensures immediate firing of the engine, by ensuring that only a slight
increase in fuel system pressure is enough to open up the injectors.
Regular operating pressures are achieved immediately durring the
engine cranking process, as the fuel pump has already been triggered
by the RPM Relay, as soon as the key is placed into the "ON", or "II"
position.

Fact #4: The Hot Start Relay was NOT intended as a remedy for a faulty
fuel system. The problem is related to the fact that the core
temperature of the engine would become cold enough to require a
*choke* to start, but the Thermo Time Switch would have been heated to
the point where it would not trip to fire of the CSV injector (95
degrees farenheit), THEN it would be needed to start the car. This is
NOT the same as a loss of rest fuel pressure that other owners describe.


As I said previously, the common DeLorean "Hot Start" problem is not
the same as the one listed in the book. We're dealing with fuel
systems that cannot maintain their fuel rest pressure. When you use
the Cold Start Valve to start the engine (be it via a "Hot Start
Relay", or manually triggering the CSV by using the 12V CPR heater
feed), you're not actually fixing the engine. All that's happening is
you're crudely carburetting the engine, while the fuel pump builds up
enough pressure to crack open the injector valves. And if you flood
the engine too much during the cranking procedure, you're can cause
long term damage such as washing out cylinders, or other damage due to
engine "dieseling". In fact, people with a "Hot-Start" issue typicly
crank their cars a bit longer when cold, than those without, because
they need the CSV to feed the engine, while the pump builds up
pressure. Hot or cold, a good system will fire the engine with no
hesitation.

Fact #6: To maintain rest pressure, the K-Jetronic system relis on a
series of check valves to maintain fuel pressure. In reality, there
are 10 possible places where leaks contributing to rest pressure loss
can occur. And they are:

1. Fuel Pump Check Valve (dependant upon type of pump used, this may,
or may not be apart of the entire fuel pump assembly)
2. Accumulator
3. Primary Pressure Regulator
4. Cold Start Injector
5/6/7/8/9/10: Individual Fuel injectors.

Now to test if any of these items are leaking, you need to use a Fuel
Pressure Gauge. Pressurize the system, let it rest for a while, and
see what happens. If the pressure drops, then you know that you've got
a leak somewhere, and you need to further examine things to see just
where that leak is occuring at. If the pressure is maintained, then
you know that the issue is electrical.

Another thing to note is on your Primary Pressure Regulator. While it
is a singular unit, there are 3 compoents in it that would be prone to
failure over time. Those being both the rubber O-rings, as well as the
metal spring inside.


What you do need to keep in mind here is that #1, new parts are NOT
always going to work properly. Manufacturing defects do occur. Next,
you say that of all the items you've replaced, you've still not hit up
the fuel injectors yet. You also describe that you've had this issue
over the past 10 years, but you haven't said at what intervals you've
taken the car in for service. It may be that the past repairs were
infact effective in addressing what they intended to fix. But
something else could have broke right after you got that repaired!
After all, this is a used car. Most importantly, you don't list the
results of what a fuel system pressure test may have been. You might
just be chasing down a red herring!


I do not believe for one second that a handful of people on this list,
out of the thousand + members here having a simular issue, constitutes
some kind of a "design flaw". What then is the explanation for the
others who do not have this problem?

If you still think this to be some sort of "design flaw" in the design
of the system, if you believe that there is some sort of a problem of
factory origin with this design, then tell me what it is?

What is your theory here as to what is causing fuel pressure loss,
that contridicts the operating theory of the fuel delivery system?
What do you believe is the problem here that is causing the issue in
your car? And most importantly, out of all of the issues addressed,
and improved parts delivered to us from the vendors over the past
quarter-century, what have they missed?

This question isn't just for you, Scott. If anyone else has any
feedback, I'd really like to hear it too.

I am not a moderator of this list. In fact, I'm still scratching my
head as to where that comment came from. But let me honestly say that
I am not trying to riddicule you, chase you off, or censure you in any
way thru a chilling effect. The goal here for everyone is to learn,
and pass on what we know. The biggest problem that I have seen here
over the years with owners posting questions isn't their lack of
knowlege. It's the lack of a structured troubleshooting flow
chart/procedure. That is what I am attempting to address here.

Now, if you don't believe that you own a high-end car, it doesn't
bother me. If it's just a toy to you, that doesn't bother me either.
But I can tell you that my experience with my own hot-start issue
comes directly from my own car which was used as a daily driver for
years, because it was my only car for that period. 6 years I've owned
my car, and studied my Workshop Manual and Parts Catalogue for 3 years
before that, and I've been on the DML for almost 10. Not impressed
with that? That's fine with me. Because accuracy of knowlege is what's
important here, not time it's been retained.

If you decide to leave this list permanently, it would be a shame. It
would be loss to both the community, and to yourself. We ourselves
don't have to get along. You and I don't have to be friends. But there
are other friendships here with others to be certain that you will
develop over time. Personally, I don't want you to be deprived of
that, so I'll ask you to please stay. However, if you do infact choose
to go ahead with your plans, don't for one second think of making me
into some sort of scapegoat for your departure...

Best wishes.

-Robert
vin 6585 "X"



--- In dmcnews@xxxxxxxxxxxxxxx, "Scot Stern" <Scotstern@xxxx> wrote:
>
> Robert,
> 
> Thank you for your response to my problem concerning the hot start.  
> Frankly, after reading it several times, it is in my opinion clearly 
> an attack / flame post.
<SNIP>







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