98 concorde starting problems

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 piss 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.

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.

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

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.

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.

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).

Reply to
aarcuda69062
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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).

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).

Reply to
aarcuda69062

Which means that none watch this ng.

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?

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

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.

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

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.

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

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

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.

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

Reply to
Matt Whiting

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

Reply to
Matt Whiting

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')

Reply to
Bill Putney

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.

Reply to
Greg Houston

So does my LH vehicle.

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

Reply to
Greg Houston

You are mistaken re: 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.
Reply to
Greg Houston

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

Must suck to be Dilbert, "eh?

Reply to
aarcuda69062

You bring up an interesting point Bill.

That fuel line was designed by an engineer.

Oooops, wait...

-You- are an engineer.

So is Matt. (but Matt flies airplanes which somehow makes him superior)

Hold it.....

Didn't you mention having designed fuel pumps at one time in your career?

Could it be?

You guys are a riot!

Reply to
aarcuda69062

Okay, I'll bite...

How exactly does the return line "reduce vapor lock?"

Reply to
aarcuda69062

Oh, maybe because they can handle higher current for longer periods of time without failing. Or, maybe they handle the same amount of current for longer periods of time without failing.

Or even, they handle lower current at a higher duty cycle without failing.

Or, maybe it has something to do with Matt performing his pre-flight check list while he's airborne?

Reply to
aarcuda69062

So where does xmirage2kx say that this is a "heat from the engine" problem.

He cites two criteria;

1) Low fuel level. So explain how low fuel level contributes to vapor lock 2) 80% of the time it's over 70 degrees and sunny out. So, explain how either of these conditions contribute to the "engine heat" situation that is germane to the TSB you keep crowing about?

Or is that you just don't get it? The TSB doesn't apply. Wrong diagnosis. Warranty claim rejected. Money spent, customer screwed again. I will not argue that there is apparently a problem of sorts that the TSB addresses, never said there wasn't.

You guys have never met a wild goose chase that you didn't love, have you?

Just proves the old adage....

A TSB in the wrong hands is dangerous.

Reply to
aarcuda69062

As explained several times earlier in the thread, a return line provides fresh fuel from the tank that has not been warmed locally from the engine to higher temperatures. Fuel returning to the tank has a higher temperature than the tank, but little more specific heat per mass due to the low volume compared to the tank volume. That is the raison d'etre of return lines on fuel injected aircraft engine systems. Today's cars use a pressurized fuel system that maintains pressure (supposedly) for a while when the engine is off and warm.

Reply to
Greg Houston

You did state, "Run the aircraft for enough hours to sufficiently heat the fuel and the problem will return I suspect." Aircraft engines are typically not run for hours on the ground during normal operations. Needing to resort to profane language does not assist your argument.

Reply to
Greg Houston

What is "they?"

Huh?

Reply to
Greg Houston

As I quoted earlier, the exact statement from the OP discussing his car is "when its low on gas, and when its hot."

Got it.

The TSB does apply.

The diagnosis is part of the TSB.

What warranty claim are you referring to in the context of what is *actually* being discussed?

No.

The vehicle is exhibiting symptoms specifically mentioned in a TSB for the same model year. It is reasonable to do the diagnosis procedures in the TSB.

Reply to
Greg Houston

Oh no! Not another guy who has a chip on his shoulder because he didn't go to college and someone else did. Sorry about that - I wish you could have gone, but not my problem.

So your logic is: (1) Some engineer did a crappy system design (2) I am an engineer (3) Therefore I am stupid too. That logic reflects on you not me, and is an extension of the chip on your shoulder (your emotion takes over your brain in certain situations so that you make irrational statements).

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

Reply to
Bill Putney

You keep bringin up the "above 70°" thing. Don't you realize that underhood temperatures (inculding fuel rail temperatures) will be directly affected by rises in ambient (i.e., a degree of ambient temp. rise will add about 1° to the rail temp.). Certainly you understand that the underhood temperatures are higher than the ambient? Perhaps you should sit in on a heat transfer class at a nearby engineering school (sorry - couldn't resist).

Also, as someone else already mentioned, perhaps the OP got ahold of some fuel with high alcohol content - combined with some other problem that is making a marginal problem an actual one. Besides the bad check valve that has been mentioned several times, a leaking injector could also explain system depressurization after shut down.

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

Reply to
Bill Putney

So, what you really meant to say is that re-circulating the fuel allows a vapor locked engine to start by supplying cooler fuel. The return line itself does nothing WRT the vapor lock condition.

Just wanted to see if you guys understand this as well as you claim you do.

Reply to
aarcuda69062

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