Concorde Fuel pressure

I have a 95 Concorde that is starting to take longer to crank than it
should. I suspect the fuel pressure regulator. I was going to pop one in as
a guess until I saw what a job it was. Looks like the intake manifold or
what ever they call it now days has to come off. Is this correct? (I've
gotta find a manual for it one of these days). Is there something else
(easier) I should try before I take this route?
Thanks
Smitty on the frozen tundra of Minnesota

Smitty wrote:
> I have a 95 Concorde that is starting to take longer to crank than it
> should. I suspect the fuel pressure regulator. I was going to pop one in as
> a guess until I saw what a job it was. Looks like the intake manifold or
> what ever they call it now days has to come off. Is this correct? (I've
> gotta find a manual for it one of these days). Is there something else
> (easier) I should try before I take this route?
> Thanks
> Smitty on the frozen tundra of Minnesota

More than likely, one of two things is happening:
(1) One or more injectors is leaky - when the car sits with engine off,
for a few hours, the fuel rail empties out into the cylinder or
cylinders with the leaky injectors. When you go to start it back up,
the fuel pump has to first re-fill the fuel rail before it can supply
and pressurize the injectors.
(2) Check valve back at fuel pump is leaky - fuel lines empty out with
similar results - pump has to refill system before cylinders see fuel
from injectors.

I don't know about 1st gen LH's, but on 2nd gens, the way to prove that
either (1) or (2) is happening is to turn key to run (not start) for a
couple of seconds, then to off, then again to run for a couple of
seconds, then to off, then to start - if it starts on the first try
after doing that, then either (1) or (2) is the problem. The reason is
that the fuel pump shuts off after a second or so if it does not detect
engine start. By cycling the key a few times, you let the pump run for
several of those second or so bursts - enough run time to refill the
rail. If you try to start without cycling the key, the single burst of
pump run time is not enough.

Pressure regulator for 2nd gens is in the fuel tank (part of sender/pump
assembly) - 1st gens are probably like that too - but not sure. But
that is probably not the problem - see (1) and (2) above.

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

Smitty wrote:

> I have a 95 Concorde that is starting to take longer to crank than it
> should. I suspect the fuel pressure regulator. I was going to pop one in as
> a guess until I saw what a job it was. Looks like the intake manifold or
> what ever they call it now days has to come off. Is this correct? (I've
> gotta find a manual for it one of these days). Is there something else
> (easier) I should try before I take this route?
> Thanks
> Smitty on the frozen tundra of Minnesota
>
>

The upper plenum has to come off (I'm assuming a 3.5L engine). Its not a
big job, really. A quick check is to pull the vacuum line off the fuel
pressure regulator and see if fuel comes out, indicating a leaky
diaphragm. Been there, done that- it caused fuel pressure leak-down over
a few hours, followed by longer than normal cranking on the next restart
to rebuild the fuel pressure and clear the leaked of fuel out of the
vacuum lines.

Bill Putney wrote:

>
> Pressure regulator for 2nd gens is in the fuel tank (part of sender/pump
> assembly) - 1st gens are probably like that too - but not sure. But
> that is probably not the problem - see (1) and (2) above.

Nope, that's one of the things they cheaped out on the second gens.
First gens have a full recirculation type fuel loop. The pressure
regulator is in the fuel rail, and fuel "bled off" by the regulator
returns to the tank, keeping cool fuel at the injectors at all times. I
think the purported reason (rather than just admitting "we're cheap" ;-)
for the change was that a recirculation system causes the fuel in the
tank to become a few degrees warmer over time, and thus increases
evaporative emissions. But the cool fuel at the injectors is sure nice
for performance and consistency.

"Smitty" > wrote in message
...
> I have a 95 Concorde that is starting to take longer to crank than it
> should. I suspect the fuel pressure regulator. I was going to pop one in
as
> a guess until I saw what a job it was. Looks like the intake manifold or
> what ever they call it now days has to come off. Is this correct? (I've
> gotta find a manual for it one of these days). Is there something else
> (easier) I should try before I take this route?
> Thanks
> Smitty on the frozen tundra of Minnesota
>
>
More then likely the fuel pump check valve is bad causing the fuel to drain
back to the tank as Bill said. The injector(s) could also cause this problem
but if that were the case you would have a hard time starting this vehicle
after a hot soak.

Glenn Beasley
Chrysler Tech

Steve wrote:
> Bill Putney wrote:
>
>>
>> Pressure regulator for 2nd gens is in the fuel tank (part of
>> sender/pump assembly) - 1st gens are probably like that too - but not
>> sure. But that is probably not the problem - see (1) and (2) above.
>
>
> Nope, that's one of the things they cheaped out on the second gens.
> First gens have a full recirculation type fuel loop. The pressure
> regulator is in the fuel rail, and fuel "bled off" by the regulator
> returns to the tank, keeping cool fuel at the injectors at all times. I
> think the purported reason (rather than just admitting "we're cheap" ;-)
> for the change was that a recirculation system causes the fuel in the
> tank to become a few degrees warmer over time, and thus increases
> evaporative emissions. But the cool fuel at the injectors is sure nice
> for performance and consistency.

OK - I stand corrected. Thanks.

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

"Steve" > wrote in message
...
> Smitty wrote:
>
> > I have a 95 Concorde that is starting to take longer to crank than it
> > should. I suspect the fuel pressure regulator. I was going to pop one in
as
> > a guess until I saw what a job it was. Looks like the intake manifold or
> > what ever they call it now days has to come off. Is this correct? (I've
> > gotta find a manual for it one of these days). Is there something else
> > (easier) I should try before I take this route?
> > Thanks
> > Smitty on the frozen tundra of Minnesota
> >
> >
>
> The upper plenum has to come off (I'm assuming a 3.5L engine). Its not a
> big job, really. A quick check is to pull the vacuum line off the fuel
> pressure regulator and see if fuel comes out, indicating a leaky
> diaphragm. Been there, done that- it caused fuel pressure leak-down over
> a few hours, followed by longer than normal cranking on the next restart
> to rebuild the fuel pressure and clear the leaked of fuel out of the
> vacuum lines.

The regulator is under the intake on this model. If the regulator is bad
there would still be fuel from the pump to the fuel rail The pump still has
a check valve built into it to prevent fuel from draining back to the tank.

As far as the fuel loop goes you have it backwards or Im just reading it
wrong. when the fuel regulator was at the intake it caused the fuel in the
tank to heat up, causing higher emissions. By having the fuel pressure
regulator on the pump in the tank, it keeps the fuel at a cooler
temperature. This is done by not having the fuel heated up by the exhaust
and under hood temperature and then going back to the tank

Glenn Beasley
Chrysler Tech

maxpower wrote:
> "Steve" > wrote in message
> ...
>
>>Smitty wrote:
>>
>>
>>>I have a 95 Concorde that is starting to take longer to crank than it
>>>should. I suspect the fuel pressure regulator. I was going to pop one in
>
> as
>
>>>a guess until I saw what a job it was. Looks like the intake manifold or
>>>what ever they call it now days has to come off. Is this correct? (I've
>>>gotta find a manual for it one of these days). Is there something else
>>>(easier) I should try before I take this route?
>>>Thanks
>>>Smitty on the frozen tundra of Minnesota
>>>
>>>
>>
>>The upper plenum has to come off (I'm assuming a 3.5L engine). Its not a
>>big job, really. A quick check is to pull the vacuum line off the fuel
>>pressure regulator and see if fuel comes out, indicating a leaky
>>diaphragm. Been there, done that- it caused fuel pressure leak-down over
>>a few hours, followed by longer than normal cranking on the next restart
>>to rebuild the fuel pressure and clear the leaked of fuel out of the
>>vacuum lines.
>
>
> The regulator is under the intake on this model. If the regulator is bad
> there would still be fuel from the pump to the fuel rail The pump still has
> a check valve built into it to prevent fuel from draining back to the tank.
>
> As far as the fuel loop goes you have it backwards or Im just reading it
> wrong. when the fuel regulator was at the intake it caused the fuel in the
> tank to heat up, causing higher emissions.

Right (allegedly).

>By having the fuel pressure
> regulator on the pump in the tank, it keeps the fuel at a cooler
> temperature.

The fuel in the TANK stays cooler without a loop, but the fuel AT THE
INJECTORS is much hotter, because intsead of continuously circulating it
just flows slowly through the rail warming up to the temperature of the
cylinder head or injector that its flowing into. That's the whole reason
that the carbureted Hemi and 440 Magnum cars of the 60s had a similar
fuel loop that pumped excess fuel from the filter back to the tank, so
that the fuel headed to the carb would be as cool as possible to prevent
vapor lock. Its not as big a deal on high pressure fuel injection, but
keeping the fuel cooler is always a little better for engine performance
and consistent mixture control.

maxpower wrote:

> As far as the fuel loop goes you have it backwards or Im just reading it
> wrong. when the fuel regulator was at the intake it caused the fuel in the
> tank to heat up, causing higher emissions. By having the fuel pressure
> regulator on the pump in the tank, it keeps the fuel at a cooler
> temperature. This is done by not having the fuel heated up by the exhaust
> and under hood temperature and then going back to the tank
>
> Glenn Beasley
> Chrysler Tech

Glenn - I'm thinking that the fuel mass in the engine compartment
environment (in the lines and fuel rail) is a *lot* less than the volume
in the tank - therefore, with a given number of calories absorbed by the
lines and rail, it's temperature rise without the full loop circulation
will be a *lot* higher than the rise in the whole tank (from the heated
fuel returning to the tank), plus heat dumped over that huge volume back
at the tank will also be dissipated at a moderate enough rate into the
ambient due to the large surface area if the tank acting as a radiator -
the net result of the full loop circulation will be lower temperature at
the point of injection into the plenum.

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

On Fri, 27 Oct 2006 06:39:42 -0400, Bill Putney >
wrote:

>Glenn - I'm thinking that the fuel mass in the engine compartment
>environment (in the lines and fuel rail) is a *lot* less than the volume
>in the tank - therefore, with a given number of calories absorbed by the
>lines and rail, it's <snip>

Possessive: "ITS"
Contractive form of the third person "to be": "IT'S"

GOTCHA!

>temperature rise without the full loop circulation
>will be a *lot* higher than the rise in the whole tank (from the heated
>fuel returning to the tank), plus heat dumped over that huge volume back
>at the tank will also be dissipated at a moderate enough rate into the
>ambient due to the large surface area if the tank acting as a radiator -
>the net result of the full loop circulation will be lower temperature at
>the point of injection into the plenum. <snip>

Putney's right here. I have an exact same, but much larger, model I
dealt with when retrofitting emergency diesel and gas turbine
generator fuel tanks back in the '90s.

Most original installations of these were much like the older FI
system....diesel or JP-4 would be pumped into a day tank, the engine
would take what it needed from there, and return excess fuel from the
pump or rail directly to the fuel tank through a separate return line.
Contractors, looking to make a extra bucks on loosely spec'd "design
and build" contracts, would replace the tank with a double wall
replacement (usually 5K gallons or more) and double wall piping, but
only a supply line would be provided, dumping the heated excess from
the engine of the generator set(s) into the day tank. The problem was
that the diesel would become dangerously hot after hours of operation,
the amount varying from model to model and by, of course, capacity.

In the projects of which I was in charge, I demanded that a double
walled return line be added to the spec to prevent this. A 10K tank
filled with #2 diesel, feeding a 750 KW generator set running at 80%
load (Cummins VT-38000/Marathon alternator), with a ground temperature
of 19°C, would heat up 4°C after 8 hours operation. However, one
"single line" installation, using the same load factor but on a 16V71T
Detroit Diesel, would heat the fuel in a 100 gallon day tank up to
almost 40°C in half the time period. Detroits run a common loop
rail/unit injector system on top of the heads, whereas the Cummins
used a PT pump with less exposure of the fuel in the cylinder head
area, so there was a little more heat transfer from the Detroit, but
the case for the dedicated return line was made, and the company's bid
specs were changed to include same.

(Note that I also wasn't stupid enough to use a Detroit Diesel for a
generator set engine! What a disaster, but the middle manager
"injuneers" at AT&T prevailed on that one. One on them was later
allowed to "retire" after rather large kickbacks involving the
supplier were uncovered and the IRS started investigating, and AT&T
got a little skittish having IRS investigators showing up back in New
Jersey.)

I would imagine the same sort of problems with hot fuel due to having
the regulator/return in the tank in a gasoline powered car would be
similar. The concern of heating of the volatiles in the fuel tank is
a non-starter, as well, since the evap system would take care of that
at start-up. I think the reason for this change was one that Frank
Zappa would full appreciate: "cheapness."