98 concorde starting problems

In article >,
Greg Houston > wrote:

> 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.

Greg, you might want to go back and re-read the OPs post, the
hard/no start occurs under two conditions;
1) Low fuel level
2) Ambient above 70 degrees

Neither one of these conditions is worth attributing to vapor
lock.
Hell, I just drove over 100 miles on Sunday in 100 degree heat in
a carbureted car with an engine mounted mechanical fuel pump, the
coolant was running at over 230 degrees, the gasoline is
reformulated **** water and I experienced absolutely no evidence
of vapor lock.

Sorry, at 72 degrees, he doesn't have vapor lock.

He has the classic pattern failure of a weak fuel pump.

> 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.

Which means that the vapor lock is a symptom, not the cause of
the problem to begin with, i.e., he has a failing fuel pump.

> 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.

All well and good, except that it doesn't fit the OPs description
of when the problem occurs.
Wrong diagnosis.

> 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.

I guess if you follow the TSB, you -might- stumble upon the root
cause for the no start.
Thing is; I have numerous customers who own 2.7 LH cars and they
do not suffer wholesale vapor lock problems with their cars under
-any- ambient temperature conditions.

> 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.

The OPs problem occurs at ambient temperature above 70 degrees
with low fuel level. No mention of a "hot engine," so the TSB
doesn't fit.
A simple amp meter hook up to the fuel pump circuit will show
lower than normal amperage draw for the fuel pump which means
it's spinning faster than normal, it's spinning faster than
normal because it's cavitating, it's cavitating because the pump
is worn out and lacks sufficient volume to maintain an adequate
level of fuel in the cup at the bottom of the fuel pump module
(via the return line) so the pump is starving.
If you guys had the slightest clue of how this system -actually-
works, and had actually paid attention to the customers
complaint, non of this back and forth crap would be necessary.

> 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.

Sounds like a fuel pump failure, not vapor lock.
Vapor lock occurs in spite of a properly functioning fuel supply.
Frankly, I haven't seen a case of vapor lock in near 25 years,
but then, I DO know to recognize the symptoms when they are
presented (like the OPs mention of missfiring when the problem
occurs).

In article >,
tim bur > wrote:

> the whole of retuirnless is the carmaker is saving money by not having a fuel
> line running bac to the tank from the engine

In order to facilitate a MPFI fuel system that does not have a
vacuum operated fuel pressure regulator it is necessary to modify
the injector driver circuit so that the injectors can be
multi-fired to achieve adequate fuel delivery, this means heavier
duty - higher quality drivers in the PCM. It's entirely likely
that the increased costs of these injector drivers offsets any
dollar saving realized by not having to use a dozen or so feet of
1/4" fuel line. Especially if one considers that the PCM is
under warranty a lot longer than the fuel line(s).

> 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

Center mounted window switches have been around a lot longer than
buss controlled body functions. Buss networked systems in and of
themselves eliminate many feet of wiring which is the whole point
of using buss circuits to begin with, so it's really not germane
to -where- the switches are positioned.
YMWTC; Japanese cars have typically had the dome light over-ride
switch built into the dome light itself (where it's reachable
from every seat position).

aarcuda69062 wrote:

> 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.

Which means that none watch this ng.


>
>
>>>>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.

Actually, I've had practical experience with both cars and airplanes and
an engineering degree that gives me a little understanding of the
subject. What is your experience and credentials?


>>>>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.

I'm not familiar with OBD2 EVAP criteria, so why don't you fill me in
since you know so much about it?


>>>>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.

Only while the pump is operating. Most vapor lock problems, both in the
old days with engine mounted pumps and carbs or today, occur while the
car or airplane is sitting after being run hard and hot. Vapor lock is
relatively rare during operation.


> 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.

It has everything to do with what we've posted and next to nothing with
what you have posted.


>>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?

I'm not familiar with LH cars, I was talking cars in general. The
routing of the fuel line is a major contributor to vapor lock
susceptibility and the reason why some cars are famous for this problem
and some rarely have it. A properl routed and insulated fuel line will
greatly reduce the likelihood of vapor forming in the fuel line.


>>>>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?

Fuel temperature is highly relevant, but not in the tank ... in the fuel
line in the engine compartment.


> 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.

Positive pressure isn't always maintained while the vehicle is sitting
with the fuel pump turned off. Check valves tend to age and leak.


>>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)

You know the root cause of one form of vapor lock, but not every form
obviously. And you seem to live in an ideal world where pressure is
always maintained between the pump and the fuel injector. Taint so.


>>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."

Sure if the maker was stupid enough to run it along side the exhaust
system. I haven't yet seen a car designed that way, but I'm sure
somebody somewhere has done it. And the heat from the pavement pales in
comparison to the heat from the exhaust manifold.

Matt

Greg Houston wrote:

>>>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.)

His ignorance of vapor lock in autos is exceeded only by his ignorance
of vapor lock formation in airplanes. :-)

Thinking that you will heat the fuel in the wings while flying is a real
hoot!

Matt

Matt Whiting wrote:
> aarcuda69062 wrote:
>
>> 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.
>
>
> Which means that none watch this ng.
>
>
>>
>>
>>>>> 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.
>
>
> Actually, I've had practical experience with both cars and airplanes and
> an engineering degree that gives me a little understanding of the
> subject. What is your experience and credentials?
>
>
>>>>> 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.
>
>
> I'm not familiar with OBD2 EVAP criteria, so why don't you fill me in
> since you know so much about it?
>
>
>>>>> 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.
>
>
> Only while the pump is operating. Most vapor lock problems, both in the
> old days with engine mounted pumps and carbs or today, occur while the
> car or airplane is sitting after being run hard and hot. Vapor lock is
> relatively rare during operation.
>
>
>> 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.
>
>
> It has everything to do with what we've posted and next to nothing with
> what you have posted.
>
>
>>> 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?
>
>
> I'm not familiar with LH cars, I was talking cars in general. The
> routing of the fuel line is a major contributor to vapor lock
> susceptibility and the reason why some cars are famous for this problem
> and some rarely have it. A properl routed and insulated fuel line will
> greatly reduce the likelihood of vapor forming in the fuel line.
>
>
>>>>> 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?
>
>
> Fuel temperature is highly relevant, but not in the tank ... in the fuel
> line in the engine compartment.
>
>
>> 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.
>
>
> Positive pressure isn't always maintained while the vehicle is sitting
> with the fuel pump turned off. Check valves tend to age and leak.
>
>
>>> 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)
>
>
> You know the root cause of one form of vapor lock, but not every form
> obviously. And you seem to live in an ideal world where pressure is
> always maintained between the pump and the fuel injector. Taint so.
>
>
>>> 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."
>
>
> Sure if the maker was stupid enough to run it along side the exhaust
> system. I haven't yet seen a car designed that way, but I'm sure
> somebody somewhere has done it. And the heat from the pavement pales in
> comparison to the heat from the exhaust manifold.
>
> Matt

You keep mentioning a bad check valve relesaing the fuel rail pressure -
don't forget a leaking injector.

Speaking of running a fuel line next to exhaust, I bought a 1980
Citation brand new - V-6. It would vapor lock after a heat soak because
they had the mechanical fuel pump mounted on the front (bumper side) of
the transverse engine, and the front bank main exhaust pipe came off the
collector pointing forward about 6" away from the fuel pump and did a
perfect 180° with the fuel pump at the exact center of radius. Nice
design!!

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

Matt Whiting wrote:

> Greg Houston wrote:
>
> >>>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.)
>
> His ignorance of vapor lock in autos is exceeded only by his ignorance
> of vapor lock formation in airplanes. :-)
>
> Thinking that you will heat the fuel in the wings while flying is a real
> hoot!

Especially since the return lines are part of the design to reduce vapor lock
during hot starts. Vapor lock isn't a problem when the engine is running, just
when you feel like starting the engine again before it cools.

aarcuda69062 wrote:

> In article >,
> tim bur > wrote:
>
> > the whole of retuirnless is the carmaker is saving money by not having a fuel
> > line running bac to the tank from the engine
>
> In order to facilitate a MPFI fuel system that does not have a
> vacuum operated fuel pressure regulator it is necessary to modify
> the injector driver circuit so that the injectors can be
> multi-fired to achieve adequate fuel delivery, this means heavier
> duty - higher quality drivers in the PCM. It's entirely likely
> that the increased costs of these injector drivers offsets any
> dollar saving realized by not having to use a dozen or so feet of
> 1/4" fuel line. Especially if one considers that the PCM is
> under warranty a lot longer than the fuel line(s).
>
> > 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
>
> Center mounted window switches have been around a lot longer than
> buss controlled body functions. Buss networked systems in and of
> themselves eliminate many feet of wiring which is the whole point
> of using buss circuits to begin with, so it's really not germane
> to -where- the switches are positioned.
> YMWTC; Japanese cars have typically had the dome light over-ride
> switch built into the dome light itself (where it's reachable
> from every seat position).

So does my LH vehicle.

I am curious what "heavier duty - higher quality drivers in the PCM" are and why
these drivers cost more

aarcuda69062 wrote:

> In article >,
> Greg Houston > wrote:
>
> > 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.
>
> Greg, you might want to go back and re-read the OPs post, the
> hard/no start occurs under two conditions;
> 1) Low fuel level
> 2) Ambient above 70 degrees
>
> Neither one of these conditions is worth attributing to vapor
> lock.
> Hell, I just drove over 100 miles on Sunday in 100 degree heat in
> a carbureted car with an engine mounted mechanical fuel pump, the
> coolant was running at over 230 degrees, the gasoline is
> reformulated **** water and I experienced absolutely no evidence
> of vapor lock.
>
> Sorry, at 72 degrees, he doesn't have vapor lock.

You are mistaken original post. xmirage2kxsaid that the problem occurs "when
its low on gas, and when its hot." He also said that 80% of the time it is over 70
degrees/sunny outside. As discussed in Chrysler's TSB, vapor lock is caused by
heat from the engine, not ambient heat, although an engine cools more slowly when
ambient temp is higher. Your experience with a carbureted car is not relevant to
the discussion; the discussion (and the Vapor Lock TSB for that matter) is about a
1998 Concorde.

In article >,
Matt Whiting > wrote:

> > Not in my control.
>
> Which means that none watch this ng.

Could you possibly be a little more absurd?

> > 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.
>
> Actually, I've had practical experience with both cars

Yet farther down you admit to having no familiarity with LH cars.

> and airplanes

I don't believe the vehicle in question is the French built SST.

> and
> an engineering degree that gives me a little understanding of the
> subject.

For all I know, you design toilet plungers.

> What is your experience and credentials?

On my resume I usually just put "dumb ****ing country mechanic."
Ya see Matt, the importance of glitzy job titles and education
bench marks lost it's luster long-long ago.


> I'm not familiar with OBD2 EVAP criteria, so why don't you fill me in
> since you know so much about it?

Gee, I guess you really don't have the practical experience as
you claim.


> > 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.
>
> Only while the pump is operating.

The TSB that Greg Houston cited mentioned "miss fires" do you
suppose they occurred while the engine was shut off?

> Most vapor lock problems, both in the
> old days with engine mounted pumps and carbs or today, occur while the
> car or airplane is sitting after being run hard and hot. Vapor lock is
> relatively rare during operation.

Oh, so all those cars that stalled in traffic, they must have
just pulled over to take a **** on the side of the road then, 'eh?

>
> > 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.
>
> It has everything to do with what we've posted and next to nothing with
> what you have posted.

Well no since the OPs symptoms occur at 70 degrees or above, that
isn't a high enough temperature to induce vapor lock.
>
>
> >>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?
>
> I'm not familiar with LH cars, I was talking cars in general.

Okay, give me a car in general where the fuel line is routed near
the exhaust manifold.

> The
> routing of the fuel line is a major contributor to vapor lock
> susceptibility and the reason why some cars are famous for this problem
> and some rarely have it.



> A properl routed and insulated fuel line will
> greatly reduce the likelihood of vapor forming in the fuel line.

And this has what to do with a car that won't start when the fuel
level is low and/or the ambients are at 70 degrees or above and
these specific symptoms lay blame to a return less fuel system
exactly how? Bear in mind, my 98 Intrepid *has* a returnless
fuel system and it started just fine on Sunday when it was over
100 degrees with 1/8th tank of fuel.

> > Fuel temperature is "irrelevant" to vapor lock?
>
> Fuel temperature is highly relevant, but not in the tank ... in the fuel
> line in the engine compartment.

I disagree. If the fuel is already heated, adding the delta T
from the engine compartment is only going to make matters worse.
>
>
> > 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.
>
> Positive pressure isn't always maintained while the vehicle is sitting
> with the fuel pump turned off. Check valves tend to age and leak.

Well, thank you Matt. Imagine, it only took this long to get to
the root cause and it's attending symptoms.
Wow, worn failed parts cause X, Y and Z to happen.

> > 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)
>
> You know the root cause of one form of vapor lock, but not every form
> obviously.

Maybe we should wait to hear from those who own second generation
LH cars with recirculating fuel systems to see if they have fewer
or more problems with vapor lock, just for the sake of fair
comparison.

> And you seem to live in an ideal world where pressure is
> always maintained between the pump and the fuel injector. Taint so.

Oh, I don't know about that Matt, I built my first fuel system
check valve leak testing tool 24 years ago from a spare radiator
pressure tester. I deal with this stuff daily, you on the other
hand obviously don't.

>
> >>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."
>
> Sure if the maker was stupid enough to run it along side the exhaust
> system. I haven't yet seen a car designed that way, but I'm sure
> somebody somewhere has done it. And the heat from the pavement pales in
> comparison to the heat from the exhaust manifold.

Earlier, you posted:
> >>typically where the fuel line runs past a hot
> >>component such as the exhaust manifold.

Would you like to borrow my napkin?

In article >,
Matt Whiting > wrote:

> Greg Houston wrote:
>
> >>>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.)
>
> His ignorance of vapor lock in autos is exceeded only by his ignorance
> of vapor lock formation in airplanes. :-)
>
> Thinking that you will heat the fuel in the wings while flying is a real
> hoot!

You can either cite where I mentioned "while flying" or summarily
go **** yourself.

Must suck to be Dilbert, "eh?