98 concorde starting problems

In article >,
Bill Putney > wrote:


> On close analysis, that explanation makes no sense (some of the heat
> will be removed to ambient in the travel back to the tank,

Oh yeah, that fuel sure is going to cool down in the whole three
seconds that it resides in the return line.

> the tank is a
> huge heat sink,

You're implying that heat sinks do not warm up.

> so if nothing else, it buys you a lot of time (more than
> no recirc) before temps at the rail rise significantly.

Where did 'temps at the fuel rail" become an issue?
Why would they be/
The fuel rail is under pressure where as the inlet to the pump is
not.

> > You and Bill may not find the above to be in the least bit
> > palatable. I suggest you take it up with the engineers who
> > design the systems, since it's their description as to why it's
> > done that way. The chief benefit being that it's easier to meet
> > OBD2 EVAP compliance, the side benefit being improved hot
> > driveability.
> >
> > I could regale you both with stories of GM police cars that
> > after 2 shifts became un-driveable because the fuel temperature
> > had risen so high that the vapor pressure allowed the purge
> > system to overwhelm the fuel delivery system.
>
> OK - but why was recirculating fuel system design used in the first
> place - it obviously costs the motherfacturers more to run a return line
> instaed of dumping it at the pressure regulator in the tank?

Proximity of the fuel pressure regulator and the attendant
manifold vacuum source, for one. Complexity and the lack of (to
that point,) OBD2 regulations.

> There must
> be a reason for its use since they could save money by not doing it. Or
> was this a lesson-learned in the industry?

I think it's pretty obvious that the industry as a whole has been
evolutionary, a large part of which has been because of lessons
learned.

In article >,
Bill Putney > wrote:

> Matt Whiting wrote:
>
> >
> > I don't know any fuel system design engineers personally. Do you?
>
> Does designing fuel pumps for 8 years count?

Just the pumps? Without knowing more specifics about who and
what application, no.

I know a whole gaggle of electrical engineers who design electric
motors, most of them can't even install a simple 4 wire trailer
light connector.

Bill Putney wrote:
> Matt Whiting wrote:
>
>>
>> I don't know any fuel system design engineers personally. Do you?
>
>
> Does designing fuel pumps for 8 years count?

Yep, but you aren't the guy who claimed that a recirc system is MORE
susceptible to vapor lock!

Matt

aarcuda69062 wrote:

> In article >,
> Matt Whiting > wrote:
>
>
>>aarcuda69062 wrote:
>>
>>>In article >,
>>> Bill Putney > wrote:
>>>
>>>
>>>
>>>>I beg to differ. Without recirc, the fuel is in the engine area a while
>>>>soaking up heat. With recirc, cool fuel is always coming in at
>>>>relatively high volume, and the warmed fuel is going back to the tank,
>>>>and any global heating of the tank by that is effectively removed by
>>>>ambient temps surrounding the tank (plus the volume of fuel there is
>>>>(relatively speaking) almost an infinite heat sink. Sre - you shut the
>>>>engine off, and it's going to heat up, but if it starts out a few
>>>>degrees cooler, chances are much better that it will never reach the
>>>>vapor stage.
>>>
>>>
>>>Doesn't work that way.
>>
>>Then how does it work?
>
>
> What are the necessary components to create a vapor lock?
>
> Is heated fuel one of them?

It is the main one. Your point?


Matt

aarcuda69062 wrote:
> In article >,
> Matt Whiting > wrote:
>
>
>>I don't know any fuel system design engineers personally. Do you?
>
>
> Personally as in ; I visit their home at least once a week for
> dinner? The answer would be no. Why would it be necessary to
> know one personally? Does one need to have a personal
> relationship with an engineer in order to avail themselves on how
> a (any) system works? I hope not, otherwise there is probably
> only a handful a people out there who are capable of servicing
> any given component or assembly on an automobile.
> Do I know any engineers? Yes.
> Do I know any Chrysler/GM/Ford engineers? Yes, I've met them on a
> regular basis during various training
> sessions/conferences/committee meetings, etc.
> Are there Chrysler engineers here, lurking? Yes
> Are they/do they laugh at the pomposity that is posted here? You
> betcha!

Then let one of them weigh in on this topic.


>>This is exactly opposite everything I've read. It would be very hard to heat
>>up all of the gas in the tank by enough to get anywhere near enough
>>vapor pressure to cause vapor lock.
>
>
> before you commit to that Matt, you might want to familiarize
> yourself with the criteria set for monitoring EVAP pressures on
> any vehicle built to 1996 or later OBD2 standards, because fuel
> heating is a very major component used in the EVAP strategy.

So?


>>It is much easier to just heat the
>>slow moving fuel in a non recirculation system.
>
>
> Please explain how the fuel in the tank is heated by engine heat
> in a non recirculating system.

It isn't, but then vapor lock doesn't occur in the tank in occurs in the
engine compartment typically where the fuel line runs past a hot
component such as the exhaust manifold.


>>This is pretty simple
>>physics. I'd like to hear your explanation as to why a non recirc
>>system will pick up less heat in the fuel before it reaches the injector.
>
>
> It would be much more interesting to hear why you think a
> recirculating system -wouldn't- raise the temperature of the fuel
> in the tank in spite of the fact that a portion of the fuel has
> traveled to the engine compartment, sat in the fuel rail for a
> period of time soaking up heat, and was returned to the tank
> repeatedly. Especially since it -is- a known occurrence and is
> something that has to be dealt with in the OBD2 EVAP strategy.

I don't think that it won't heat the fuel in the tank. However, since
that is largely irrelevant to vapor lock, what does it matter? What
matters is when the fuel in the fuel line vaporizes before reaching the
carbuertor or fuel injector. And the temperature of the fuel in the
fuel lines in the engine compartment will be much higher in a
non-recirculating system that has a low flow rate and thus higher dwell
time near the hot components of the engine.


Matt

the whole of retuirnless is the carmaker is saving money by not having a fuel
line running bac to the tank from the engine
that is alos why u see more window switches in the center console as in
libertys and pt bruisers less wiring since it runs onma bus circuit

aarcuda69062 wrote:

> In article >,
> Bill Putney > wrote:
>
> > Yes - I knew that - *BUT* for the purposes of preventing vapor lock in
> > the engine area, it does no good, don't you think? The recirc in the
> > tank consist of the pressure regulator (at the tank) dumping excess fuel
> > back to the tank from the pressure relief valve - not the same thing as
> > recirc'ing all the way from the fuel rail. With under hood temperatures
> > rising over the years, that's one of the reasons they had to abandon the
> > engine-mounted fuel pump and recirc the fuel. I guess the Chrysler
> > engineers forgot about that lesson learned.
>
> Less chance of vapor lock with the return less system since the
> fuel does not pick up engine heat (the whole point of the return
> less system).

In article >,
Matt Whiting > wrote:

> aarcuda69062 wrote:
> > In article >,
> > Matt Whiting > wrote:
> >
> >
> >>I don't know any fuel system design engineers personally. Do you?
> >
> >
> > Personally as in ; I visit their home at least once a week for
> > dinner? The answer would be no. Why would it be necessary to
> > know one personally? Does one need to have a personal
> > relationship with an engineer in order to avail themselves on how
> > a (any) system works? I hope not, otherwise there is probably
> > only a handful a people out there who are capable of servicing
> > any given component or assembly on an automobile.
> > Do I know any engineers? Yes.
> > Do I know any Chrysler/GM/Ford engineers? Yes, I've met them on a
> > regular basis during various training
> > sessions/conferences/committee meetings, etc.
> > Are there Chrysler engineers here, lurking? Yes
> > Are they/do they laugh at the pomposity that is posted here? You
> > betcha!
>
> Then let one of them weigh in on this topic.

Not in my control.

>
> >>This is exactly opposite everything I've read.

I would (belatedly) interject here that apparently all you've
got to go on is what you've read, and it's certain that you may
not have read all that is necessary, and it's also certain that
you lack practical experience.

> >>It would be very hard to
> >>heat
> >>up all of the gas in the tank by enough to get anywhere near enough
> >>vapor pressure to cause vapor lock.
> >
> >
> > before you commit to that Matt, you might want to familiarize
> > yourself with the criteria set for monitoring EVAP pressures on
> > any vehicle built to 1996 or later OBD2 standards, because fuel
> > heating is a very major component used in the EVAP strategy.
>
> So?

So, apparently it is not "very hard to heat up all the gas in the
tank by enough to get anywhere near enough vapor pressure to
cause vapor lock." If you knew anything about OBD2 EVAP
criteria, you'd be familiar with the pressure built and the
conditions where they are maximum.

>
> >>It is much easier to just heat the
> >>slow moving fuel in a non recirculation system.
> >
> >
> > Please explain how the fuel in the tank is heated by engine heat
> > in a non recirculating system.
>
> It isn't,

That equals a head start as far as the fuel system is concerned.

> but then vapor lock doesn't occur in the tank in occurs in the
> engine compartment

Hog wash. Vapor lock is more likely to occur on the suction side
of the pump and is virtually non existent on the pressure side of
the pump up too the point where there is a component problem such
as a failing fuel pump.
You could easily win this by describing in detail the precise
movements of the fuel in the tank to the pump, from the pump to
the filter/regulator and its return to the fuel tank in an LH
chassis and include the where and why that causes the (cited in
TSB by Greg Houston) vapor lock condition. IOWs, cite the
specific failure mode that contributes to the vapor lock.
(hint, it's got nothing to do with anything you or Bill have
posted so far). I'll tell you this much; Chryslers description
using the words "vapor lock" is a bit disingenuous.

> typically where the fuel line runs past a hot
> component such as the exhaust manifold.

I'm under the hoods of a lot of LH cars, exactly where is this?

>
> >>This is pretty simple
> >>physics. I'd like to hear your explanation as to why a non recirc
> >>system will pick up less heat in the fuel before it reaches the injector.
> >
> >
> > It would be much more interesting to hear why you think a
> > recirculating system -wouldn't- raise the temperature of the fuel
> > in the tank in spite of the fact that a portion of the fuel has
> > traveled to the engine compartment, sat in the fuel rail for a
> > period of time soaking up heat, and was returned to the tank
> > repeatedly. Especially since it -is- a known occurrence and is
> > something that has to be dealt with in the OBD2 EVAP strategy.
>
> I don't think that it won't heat the fuel in the tank. However, since
> that is largely irrelevant to vapor lock, what does it matter?

Fuel temperature is "irrelevant" to vapor lock?
Does raising the pressure of a liquid tend to increase or
decrease its boiling point?
Pick a point in the fuel system where the fuel goes from a
negative pressure to a positive pressure and then cite why the
side under positive pressure is (according to you) more likely to
boil of form into a vapor.

> What
> matters is when the fuel in the fuel line vaporizes before reaching the
> carbuertor or fuel injector.

Again, vapor lock on the pressure side of the fuel is quite rare
and would probably take some pretty extreme temperatures to
facilitate. And, in the case of the LH cars, it doesn't occur
there to begin with, it starts at the inlet to the fuel pump.
(you can go ahead and do the math since I already know what the
root cause of the LH vapor lock is)

> And the temperature of the fuel in the
> fuel lines in the engine compartment will be much higher in a
> non-recirculating system that has a low flow rate and thus higher dwell
> time near the hot components of the engine.

This totally ignores the fact that the fuel can pick up heat on
the return path from things like the pavement and/or the exhaust
system. But then, you -did- say that fuel temperature was
"irrelevant."

aarcuda69062 wrote:

> I would (belatedly) interject here that apparently all you've
> got to go on is what you've read, and it's certain that you may
> not have read all that is necessary, and it's also certain that
> you lack practical experience.
>
> > >>It would be very hard to
> > >>heat
> > >>up all of the gas in the tank by enough to get anywhere near enough
> > >>vapor pressure to cause vapor lock.
> > >
> > >
> > > before you commit to that Matt, you might want to familiarize
> > > yourself with the criteria set for monitoring EVAP pressures on
> > > any vehicle built to 1996 or later OBD2 standards, because fuel
> > > heating is a very major component used in the EVAP strategy.
> >
> > So?
>
> So, apparently it is not "very hard to heat up all the gas in the
> tank by enough to get anywhere near enough vapor pressure to
> cause vapor lock."

There is no indication of that all, either in your posting or the Chrysler
service bulletin regarding the vehicle in question.

> If you knew anything about OBD2 EVAP
> criteria, you'd be familiar with the pressure built and the
> conditions where they are maximum.

Exactly which OBD2 criteria are you referring to?

>
>
> >
> > >>It is much easier to just heat the
> > >>slow moving fuel in a non recirculation system.
> > >
> > >
> > > Please explain how the fuel in the tank is heated by engine heat
> > > in a non recirculating system.
> >
> > It isn't,
>
> That equals a head start as far as the fuel system is concerned.
>
> > but then vapor lock doesn't occur in the tank in occurs in the
> > engine compartment
>
> Hog wash. Vapor lock is more likely to occur on the suction side
> of the pump and is virtually non existent on the pressure side of
> the pump up too the point where there is a component problem such
> as a failing fuel pump.

There are service bulletins issued by Chrysler for vapor lock conditions on the
pressure side in the pump (more specifically inside the engine compartment) for
some M.Y. 1998 LH vehicles.




>
> You could easily win this by describing in detail the precise
> movements of the fuel in the tank to the pump, from the pump to
> the filter/regulator and its return to the fuel tank in an LH
> chassis and include the where and why that causes the (cited in
> TSB by Greg Houston) vapor lock condition. IOWs, cite the
> specific failure mode that contributes to the vapor lock.
> (hint, it's got nothing to do with anything you or Bill have
> posted so far). I'll tell you this much; Chryslers description
> using the words "vapor lock" is a bit disingenuous.
>
> > typically where the fuel line runs past a hot
> > component such as the exhaust manifold.
>
> I'm under the hoods of a lot of LH cars, exactly where is this?

The hot component cited for sure is the engine cooling lines, at least for the
2.7L engine.

>
>
> >
> > >>This is pretty simple
> > >>physics. I'd like to hear your explanation as to why a non recirc
> > >>system will pick up less heat in the fuel before it reaches the injector.
> > >
> > >
> > > It would be much more interesting to hear why you think a
> > > recirculating system -wouldn't- raise the temperature of the fuel
> > > in the tank in spite of the fact that a portion of the fuel has
> > > traveled to the engine compartment, sat in the fuel rail for a
> > > period of time soaking up heat, and was returned to the tank
> > > repeatedly. Especially since it -is- a known occurrence and is
> > > something that has to be dealt with in the OBD2 EVAP strategy.
> >
> > I don't think that it won't heat the fuel in the tank. However, since
> > that is largely irrelevant to vapor lock, what does it matter?
>
> Fuel temperature is "irrelevant" to vapor lock?

I don't think he indicated anything like the question you propose.

>
> Does raising the pressure of a liquid tend to increase or
> decrease its boiling point?
> Pick a point in the fuel system where the fuel goes from a
> negative pressure to a positive pressure and then cite why the
> side under positive pressure is (according to you) more likely to
> boil of form into a vapor.

The vapor lock problem occurs while the engine is off. If pressure is not
maintained while the engine is off (but the engine is still warm) the vapor lock
problem can occur. The first step for diagnosis in Chrysler's service bulletins
is to check if fuel pressure is maintained for 15 minutes after the fuel pump is
turned on, then off.

>
>
> > What
> > matters is when the fuel in the fuel line vaporizes before reaching the
> > carbuertor or fuel injector.
>
> Again, vapor lock on the pressure side of the fuel is quite rare
> and would probably take some pretty extreme temperatures to
> facilitate. And, in the case of the LH cars, it doesn't occur
> there to begin with, it starts at the inlet to the fuel pump.
> (you can go ahead and do the math since I already know what the
> root cause of the LH vapor lock is)

Careful there, your statement is resembling begging the question. First Chrysler
published a TSB for vapor lock conditions on the pressure side of the fuel pump.
Second, what math are you referring to? If you honestly know some math which
supports your position don't be afraid to post it. You may already "know" what
the root cause of the LH vapor lock is, but Chrysler published a service
bulletin that disagrees with your diagnosis. Given the choice, I'll lean
toward Chrysler's analysis and repair.

>
>
> > And the temperature of the fuel in the
> > fuel lines in the engine compartment will be much higher in a
> > non-recirculating system that has a low flow rate and thus higher dwell
> > time near the hot components of the engine.
>
> This totally ignores the fact that the fuel can pick up heat on
> the return path from things like the pavement and/or the exhaust
> system. But then, you -did- say that fuel temperature was
> "irrelevant."

To be fair, you've made an irrelevant conclusion policy here. His "irrelevant"
comment was only referring to the temperature of gasoline in the Fuel Tank, not
any fuel temperature anywhere. As stated in Chrysler's own bulletin, the vapor
lock problem occurs near the hot engine, not in the tank. However according to
the TSB the fuel pump module is a source of the problem due to its inability to
maintain fuel pressure after being switched OFF.

aarcuda69062 wrote:

> In article >,
> Greg Houston > wrote:
>
> > Maybe if the fuel tank was almost empty and the little amount of fuel
> > returning to the pump was enough to almost make a measurable change in
> > temperature to the fuel in the pump. Otherwise I don't see how that
> > would be much of an issue.
> > The advantage of a return line is that you
> > can pump plenty of liquid gasoline through the system to keep it
> > continuously cool enough to avoid vaporization in the lines.
>
> The fuel ahead of the pump is at 35-40 psi, at that pressure, it
> isn't at all susceptible to vapor lock. Doesn't mean it can't
> happen, but as it's been since the advent of EFI, usually the
> only time vapor lock becomes an issue is when the gasoline supply
> is blended for winter and a geographic area receives an unusual
> for the season warm/hot spell which makes it a specific function
> of the gasoline's vapor pressure.

It's only at 35-40 psi after the engine is shut off (while the engine remains
warm) IF the fuel module is working properly.

> > This is
> > similar to a garden hose sitting in the sun that is full of hot water
> > but if you keep running fresh water though it, it stays fairly cool even
> > though it is still in the sun.
>
> Not at all like a garden hose, the fuel lines do not sit in the
> sun like your garden hose does, soaking up heat. Also, once
> purged of the hot water from the sun soak, your garden hoses
> supply of water comes from underground where the ambient ground
> temperature keeps it cool(er).
> Bad analogy

Actually the fuel line is adjacent to warm engine components, where they can
soak up heat. The TSB states as much as well. It is also why the TSB refers
to modifying engine cooling lines. The combination of the fuel lines
absorbing engine heat and a malfuntioning fuel pump that doesn't keep pressure
high enough after it is shut off causes the vapor lock condition.

>
>
> > Vapor lock has been a hot starting issue for some piston aircraft
> > engines with fuel injected engines. When return lines are used it
> > becomes less of an issue as running the electric fuel pumps for a short
> > while is an item on the pre-start checklist.
>
> A purge function which is separate from the causing event.
> Run the aircraft for enough hours to sufficiently heat the fuel
> and the problem will return I suspect.

Not at all. Running the fuel pump is a warm engine start checklist item.
(i.e. after the aircraft has been run for hours.)

> > I'm not sure what the PCM update (mentioned in the TSB I posted in a
> > separate message) does, but it probably turns on the fuel pump a little
> > longer before cranking or some similar trick.
>
> Or; they increase the pulse width of the injectors to purge
> vapors. Running the fuel pump longer would do nothing since
> there's no recirculation involved, so what if anything would it
> do?
>
> > On my 99 (built after
> > they fixed the problem in the TSB) I can hear the fuel pump come on for
> > a second or two when I turn the key to ON before START.
>
> Same as any other EFI car.

With the LDP you can also hear the LDP sequence (only when starting an engine
that is cold [it doesn't do it when it is really really cold in the winter).
In later years CA cars used another technology in lieu of the LDP--I think
around MY 2001 or 2002.

>
>
> > On the other
> > hand I have a California Emissions-Certified vehicle that needs a leak
> > detection pump which may work differently then vehicles sold in the
> > other 45 or so states that did not use this type of pump.
>
> Nope. AFAIK, LDPs are used federally also, I see enough of them
> for service here in Wi.

According to the Chrysler '99 LH service manual the LDP was only on CA
emissions cars, at least for that MY.

Greg Houston wrote:

> aarcuda69062 wrote:
>
> > In article >,
> > Greg Houston > wrote:
> >
> > > Maybe if the fuel tank was almost empty and the little amount of fuel
> > > returning to the pump was enough to almost make a measurable change in
> > > temperature to the fuel in the pump. Otherwise I don't see how that
> > > would be much of an issue.
> > > The advantage of a return line is that you
> > > can pump plenty of liquid gasoline through the system to keep it
> > > continuously cool enough to avoid vaporization in the lines.
> >
> > The fuel ahead of the pump is at 35-40 psi, at that pressure, it
> > isn't at all susceptible to vapor lock. Doesn't mean it can't
> > happen, but as it's been since the advent of EFI, usually the
> > only time vapor lock becomes an issue is when the gasoline supply
> > is blended for winter and a geographic area receives an unusual
> > for the season warm/hot spell which makes it a specific function
> > of the gasoline's vapor pressure.
>
> It's only at 35-40 psi after the engine is shut off (while the engine remains
> warm) IF the fuel module is working properly.
>
> > > This is
> > > similar to a garden hose sitting in the sun that is full of hot water
> > > but if you keep running fresh water though it, it stays fairly cool even
> > > though it is still in the sun.
> >
> > Not at all like a garden hose, the fuel lines do not sit in the
> > sun like your garden hose does, soaking up heat. Also, once
> > purged of the hot water from the sun soak, your garden hoses
> > supply of water comes from underground where the ambient ground
> > temperature keeps it cool(er).
> > Bad analogy
>
> Actually the fuel line is adjacent to warm engine components, where they can
> soak up heat. The TSB states as much as well. It is also why the TSB refers
> to modifying engine cooling lines. The combination of the fuel lines
> absorbing engine heat and a malfuntioning fuel pump that doesn't keep pressure
> high enough after it is shut off causes the vapor lock condition.
>
> >
> >
> > > Vapor lock has been a hot starting issue for some piston aircraft
> > > engines with fuel injected engines. When return lines are used it
> > > becomes less of an issue as running the electric fuel pumps for a short
> > > while is an item on the pre-start checklist.
> >
> > A purge function which is separate from the causing event.
> > Run the aircraft for enough hours to sufficiently heat the fuel
> > and the problem will return I suspect.
>
> Not at all. Running the fuel pump is a warm engine start checklist item.
> (i.e. after the aircraft has been run for hours.)
>
> > > I'm not sure what the PCM update (mentioned in the TSB I posted in a
> > > separate message) does, but it probably turns on the fuel pump a little
> > > longer before cranking or some similar trick.
> >
> > Or; they increase the pulse width of the injectors to purge
> > vapors. Running the fuel pump longer would do nothing since
> > there's no recirculation involved, so what if anything would it
> > do?
> >
> > > On my 99 (built after
> > > they fixed the problem in the TSB) I can hear the fuel pump come on for
> > > a second or two when I turn the key to ON before START.
> >
> > Same as any other EFI car.
>
> With the LDP you can also hear the LDP sequence (only when starting an engine
> that is cold [it doesn't do it when it is really really cold in the winter).
> In later years CA cars used another technology in lieu of the LDP--I think
> around MY 2001 or 2002.
>
> >
> >
> > > On the other
> > > hand I have a California Emissions-Certified vehicle that needs a leak
> > > detection pump which may work differently then vehicles sold in the
> > > other 45 or so states that did not use this type of pump.
> >
> > Nope. AFAIK, LDPs are used federally also, I see enough of them
> > for service here in Wi.
>
> According to the Chrysler '99 LH service manual the LDP was only on CA
> emissions cars, at least for that MY.

Oops, strike that last sentence. I just confirmed with my copy of the LH manual.
Leak Detection Pumps may be found on non-CA emissions cert. vehicles.