98 concorde starting problems

aarcuda69062 wrote:
> less - chance - of - vapor - lock - with - a - return - less -
> system. The - fuel - doesn't - pick - up - engine - heat - which
> - is - carried - back - to - the - tank - raising - the -
> temperature - of - the - entire - fuel - supply - making - it -
> more - susceptible - to - vapor - lock.


On close analysis, that explanation makes no sense (some of the heat
will be removed to ambient in the travel back to the tank, the tank is a
huge heat sink, so if nothing else, it buys you a lot of time (more than
no recirc) before temps at the rail rise significantly.

> 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? 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?

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

xmirage2kx wrote:

> I have a 1998 chrysler concorde LXi. Every so often it wont start, and
> its happening more and more. so far there are only 2 conditions that
> it wont start that often. when its low on gas, and when its hot.
>
> engine will turn over, it just wont start. every so often it does start,
> and it feels like its missing quite a bit (3-4 cylinders). then other
> times it runs like a champ. aften it gets running (even when it feels
> like its missing) I rev the engine a few mins and it will run fine till its off.

Ok some other people have mentioned some TSBs so you may already have
this info.

There are several TSBs for a 98 Concorde which may apply to your problem.

18-14-98 In Stock/Transit Flash Update to Minimize Vapor Lock Concerns.

- and -

18-09-98B (6/12/1998) NO RESTART/ROUGH IDLE AFTER A HOT SOAK - PCM - REVISED

This second TSB supercedes two earlier TSBs with the same title
18-09-98 (Feb 27 1998) 18-09-98A (March 13 1998) Be sure you're
looking at the last version.

----------------------------------------
TSB 18-09-98B NO RESTART/ROUGH IDLE AFTER A HOT SOAK -PCM- REVISED
(Jun 12 98)
Applies to all vehicles built before May 12, 1998. (2.7L t'stat mod
applies to vehicles built after Apr 20, 1998). Check your VIN if you're
not sure when your vehicle was built.

Symptom: Hot engine no start, hot engine restart w/ rough idle, or hot
engine start/die-out. May have misfire DTCs. ... May not restart until
cools. Fuel vapor build up in the fuel rail may be the cause.

The summary diagnosis for 18-09-98B basically is to Check codes and
repair as necessary prior to proceeding. Cold soak the vehicle for min.
of 8 hours. Connect a fuel pressure gauge (Miller Tool # C4799) to svc
port. Switch key to RUN while monitoring pressure but do NOT start
engine. Allow fuel pressure to stabilize (48-50 psi) and switch to OFF.
Monitor pressure for 15 mins. If fuel pressure drops 20 psi or more
perform flash update repair procedure only. Additionally if vehicle
has 2.7L perform thermostat mod. and heater hose mod. repair procedures.

The fix-it section starts with replacing the fuel pump module (if
necessary per diagnostics I paraphrased above) and then flashing the
PCM. [Release 21 or higher and TIL CD Release 1161 or higher]. For
the 2.7L engine (which I don't think you have b/c you said Concorde LXi
not LX) there are additional mods to the cooling system involving hoses.
The full procedures are too detailed to post here.

-----------------------------
TSB 18-14-98 Flash Update to Minimize Vapor Lock Concerns. (Mar 13 1998)
This TSB applies to 3.2 L engine vehicles built prior to Feb 16 1998 MDH
(0216XX) and 2.7L engine vehicles built prior to Mar 9 1998 MDH (0309XX).

There is no diagnosis section. Basically it has step by step
instructions to erase and reprogram the PCM and seems to be a subset of
the TSB 18-09-98B above, except it was written a little earlier so it
has a lower software release number specified as the minimum to use. It
lists that the MDS and DRB must have Release 21 or higher and TIL CD
release 1153 or higher.

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?


Matt

aarcuda69062 wrote:

> In article >,
> Matt Whiting > wrote:
>
>
>>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).
>>
>>What?
>
>
> less - chance - of - vapor - lock - with - a - return - less -
> system. The - fuel - doesn't - pick - up - engine - heat - which
> - is - carried - back - to - the - tank - raising - the -
> temperature - of - the - entire - fuel - supply - making - it -
> more - susceptible - to - vapor - lock.
>
> 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 don't know any fuel system design engineers personally. Do you? 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. It is much easier to just heat the
slow moving fuel in a non recirculation system. 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.


Matt

aarcuda69062 wrote:

> less - chance - of - vapor - lock - with - a - return - less -
> system. The - fuel - doesn't - pick - up - engine - heat - which
> - is - carried - back - to - the - tank - raising - the -
> temperature - of - the - entire - fuel - supply - making - it -
> more - susceptible - to - vapor - lock.

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. 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.

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.

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. 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. 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.

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.
>
> 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...

I think you're forgetting that this car does not do recirc (I don't
count pressure relief valve dumping at the tank a true recirc).

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

Matt Whiting wrote:

>
> I don't know any fuel system design engineers personally. Do you?

Does designing fuel pumps for 8 years count?

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

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?

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!

> 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.

> 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.

> 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.

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.

> 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

> 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.

> 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.

> 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.