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93 Chrysler Lebaron won't start when engine warm


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loganr
New User

Mar 15, 2010, 12:08 PM

Post #1 of 4 (4023 views)
93 Chrysler Lebaron won't start when engine warm Sign In

1993 Chrysler Lebaron
3.0L V6
116k miles

When the car has not been run for a few hours (engine cold) it starts up perfectly and can be driven normally. But once the car is warmed up to running temperature, if you shut it off and let it sit a minute it will not start. The engine cranks fine. Once in a while it will catch but stumble and stop. But the car is not going anywhere unless you let it sit a few hours.

I am suspicious of the fuel pump. When this condition occurs, if I turn the key, I can hear the relay click but I don't hear the pump prime. Even if I let it sit 20 minutes or so and come back, still I can't hear the pump priming. But if I go out first thing in the morning, when I turn the key to on position (without cranking) I can hear the pump priming.

I did change the fuel pump relay just for good measure. I have not yet tested for spark on the hot engine but I will do that this afternoon. Still, I'm really bothered by why I don't hear the fuel pump. I think the engine is not starting for lack of fuel.

Now I'm looking for ideas - is this symptom something that has a few common causes? What should I be checking? I'm hoping to solve this one myself without resorting to a shop.


steve01832
Veteran
steve01832 profile image

Mar 15, 2010, 5:05 PM

Post #2 of 4 (4012 views)
Re: 93 Chrysler Lebaron won't start when engine warm Sign In

You need to start by checking fuel pressure with a guage, spark, and injector pulse. While the engine is not starting, you must check all of these systems at the same time. Post back with the results and we can go further.

Steve


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Mar 16, 2010, 5:12 PM

Post #3 of 4 (4002 views)
Re: 93 Chrysler Lebaron won't start when engine warm Sign In

loganr; Agree with Steve. Another thing to check, as was common to that vintage Chrys., was overfueling from faulty CTS (coolant temp sensor) and MAP (manifold absolute pressure sensor). Since it starts and runs okay when cold (needing a rich mixture), but doesn't when warm........just a thought. Next time it acts up, try holding the throttle to the floor while cranking over the engine. By doing this (WOT) wide open throttle, this does two things. Shuts off fuel supply and gives the engine extra air to compensate for a flooded engine. If it starts, back off of the throttle as the engine recovers so that you don't over-rev it.
Loren
SW Washington


loganr
New User

Mar 17, 2010, 8:56 AM

Post #4 of 4 (3997 views)
Re: 93 Chrysler Lebaron won't start when engine warm Sign In

I checked spark and it's OK. The plugs are worn but there is spark. I don't have a fuel pressure gauge yet. I'm trying to locate one before I break down and buy one. I also tried the WOT trick but that didn't change anything - the engine still would not catch.

When the symptom was occurring, I opened up the air intake pipe and sprayed in some starter fluid. The car started right up but did not stay running. Since I'm not hearing the fuel pump prime I'm becoming convinced it's related. It was even more convincing this morning when the symptom occurred on a cold engine. It could have just been coincidence that it always occurred hot. I've only had the vehicle for a few days.

I removed the wiring connection from the fuel pump, cleaned it a little, and put it back on. The engine fired right up after. I am going to check all the wiring involved and make sure I don't have a loose connection somewhere. Hopefully I can get the symptom to occur again so I can test whether there is power coming to the fuel pump or if the pump is just flaky.

Thanks for the suggestions so far. I'll keep you posted.






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