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98 Concord Lxi starting problems

I have a 98 Chrysler Concord Lxi with a 3.2 L V6. I live in Indiana and in the summer time when its hot The car will get warmer than normal (I have figured out that one of the cooling fans is out and needs to be replaced). That said. after running for a few hours on the highway and if sat idle with the temperature raised, if I shut the car off 9 times out of 10 when I go to restart the car it will crank and crank but will not fire.My guess is the computer shuts the fuel off. I have to wait about 30 minutes and it will start. Sometimes it will start very rough with a carbon smell and the need to idle it high until it smooths out. Other times It will start with out having to wait but the idle is again rough and can smell carbon. I have looked online and found some have a solution of releasing the pressure of the fuel line as it could be a symptom of vapor lock. I have tried this and no pressure is released ( I have disconnected A/C Lines on previous cars only to find a large BOOM a mess in the garage and in my shorts!) so I know I am releasing the right Scraeder valve.

If there is no fuel pressure at the fuel rail while cranking the engine it is likely the fuel pump is failing. This can be verified with a fuel pressure gauge and a volt meter or test light at the pump connector.

Years ago when a vehicle like this came to the shop and we didn’t feel like pushing it in, one person would strike the bottom of the fuel tank with a mallet while another cranks the engine. This usually gets the pump working temporarily to drive it into the shop. If this allows your car to start replace the fuel pump.

The problem could be vapor lock.

On a fuel injected engine, when the fuel pump stops running the fuel rails should hold residual fuel pressure. This is what prevents vapor lock. If the fuel pressure drops to zero as soon as the fuel pump stops running you get vapor lock.

One way to check for this is to connect a fuel pressure gauge, turn the ignition to run position to operate the fuel pump and then turn the ignition off. Then watch the gauge to observe how quickly the residual fuel pressure drops off. It should take 15-20 minutes for the residual fuel pressure to bleed down.

Or the shade tree method to check for vapor lock is to carry a bottle of water in the vehicle. The next time the engine doesn’t start, open the hood and pour the bottle of water over the fuel rails to cool them off. If the engine starts that’s vapor lock.

Tester

To see if the starting trouble is due to a lack of fuel simply spray a small amount of starter fluid into the intake. If it is just a fuel delivery issue the engine will fire right up. If that proves out to be the case I would first suspect the fuel pump relay, then the fuel pump and wiring to it. You may want to replace the fuel filter also.

Do you have a spark tester?

When it doesn’t start, immediately hook up the spark tester and crank it over. You should have a bright blue spark

If nothing else, it’ll narrow down your list of suspects

Another thing I would do is hook up a fuel pressure gauge to the fuel rail and just leave it there. Then when it won’t start, pop the hood and look at the gauge. If it reads 0, you’ve narrowed it down some more

I recently ran into a no start situation. The very first thing I did is hook up the fuel gauge and leave it there. Then when it didn’t start, I popped the hood, and the pressure was fine. I hooked up that spark tester and got no spark. It turned out the be the crankshaft position sensor. After driving the car and shutting it off, the heat soak would cause the sensor to go open

Just throwing some ideas out there . . .

I will Have to install a fuel pressure gauge, that’s a good idea. It seems to only do it when its hot out side, or the cars temperature is higher than normal for a long period of time. I should have asked this during the summer, but truth be told I had forgotten about CarTalk until last week and then the sad news. I am one of those that did not realize the brothers had retired and continued listening to the show as if it was still on air.

I figured if anyone would know how to figure this out they would! Everything that I can think of still makes me think this is a vapor lock situation as well. I can almost guarantee when it will not start, but now that its getting colder those chances are less. If I don’t have a spark tester I know my dad does. He might even have mine.

If the weather now is colder, would i still get an accurate reading of the residual pressure?

Thanks for the ideas guys I appreciate it.

Frankly, I really doubt the problem is due to vapor lock. If it is a fuel problem the starter fluid trick will confirm it.

Reason why I thought it is vapor lock as well is because it seems to only happen when its really hot, and the fuel has a larger area to “vaporize” does that make sense? I might be thinking out of my butt completely now. Non the less. It only seems to happen when the ambient temp is in the 80-90 range in city traffic

Back in the day of carburetors I would totally agree with your thought on that but not so much with todays injected cars. I suppose what you say may and does still happen but it has to be pretty rare. Now a fuel pump relay with bad contacts that get hot and make a bad power connection to the pump that is something I could really see, or a bad wire connection in the line to the pump that heats up and that causes more voltage drop across the bad connection and kills the pump. Those are things I would be looking for. The real trouble could be with the ignition system rather than the fuel system. Problems occurring with ignition systems when they get hot are pretty common. Once again, the starter fluid trick will tell the story of what is true.