2002 starts inconsistently

[MarquisGT]

I have a 2002 LeSabre with 95,000 miles that occasionally won't start. It's getting more frequent, and now I'm afraid to drive the car at all. Sometimes it starts perfectly normal, and other times it attempts to start... the starter cranks, and the engine kicks over, but runs very rough for a couple seconds and dies. Any attempts to restart it again for 30-60 minutes are unsuccessful, but after that time period it will usually start again and run perfectly normal.

I can start it with a little extra gas, and it will run smooth and fine as long as I keep the RPMs at 1,500 or more. Below that it runs rough and dies.

Engine or air temperature don't seem to be a problem. It happens on cold starts and warm starts.

I found a few threads suggesting fuel additives, higher octane fuels, and VATS problems... but those don't seem to help.

Any ideas??

[Ralph123]

Does your check engine light come on? If so, you'll need to get the codes.

[MarquisGT]

Nope, no check engine light. No warning lights at all.

[Robdaparamedic]

I have the same year and the same problem. It has happened about 4 times with no explanation. MY "service engine soon" light was on and the code was P0420. Emissions catylst ect...ect... When googling this, I have found there are several things it could be from a catylectic convertor to a missfire from a bad wire or plug and low fuel pressure.
I have found a few things that have made a difference although only time will tell. I thought, at first, this was the fuel sending unit but there is no way of checking this unless you have a fuel pressure guage and put it on when it doesn't start. You should have 42psi of pressure when working properly. Secondly, what I have found is, the wires were shorting out and had excessive condensation from the edge of the boots, right at the coil packs. The boots were touching and this was causing the cylinders to short out. Here's something to check while the car is running, touch the wires coming off the coil packs. OBVIOUSLY, you might feel a shock. I had 2 bad wires, even after I moved them away from each other and there was no visible water, I would still get a shock touching them. I have since replaced the wires and plugs and the car seems to be running much better. Originally I replaced them with some cheap shhhht wires and it seems you get what you pay for. The only other thing I have been doing is putting some dry gas in the tank every 4th fill up, or so. Hope this helps. I know how it feels to wonder if the car is going to start or not every time you park it. Good Luck !!

Rob

[Ralph123]

Do you smell gas anywhere? The fuel pressure regulators are known to fail. What's your fuel pressure?

[MarquisGT]

I checked the fuel pressure and it was 44-46 PSI at idle. When I removed he vacuum line to the pressure regulatory it went to 54 Psi. The book says it should be 48-55, so I think that's close enough, right?
Of course, this was all when the car was starting and running fine...I couldn't get it to act up. It'll carry the tester with me for a few days and see if I can catch it when it won't start...but I don't think it's a fuel problem. I have Lucas gas treatment in the tank and I checked the resistance on all the injectors. All the plug wires look OK physically an I know it's not missing any cylinders.
Any other ideas?
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[Rasp]

Personally I think it sounds like a fuel pump.

I can start it with a little extra gas, and it will run smooth and fine as long as I keep the RPMs at 1,500 or more. Below that it runs rough and dies.

sounds like your pump is weak when it does this. I know you said that it runs fine at other times but I have a feeling your pump is on its way out.

That or maybe your fuel filter is clogged up a bit.

[MarquisGT]

I just checked the fuel pressure while it wouldn't start... exactly the same psi. 46 Psi when key is in run, and while cranking. When I force it to start with extra gas and 1500 rpm, it still reads 46 the whole time.
I wonder I it's a catalytic converter problem??
Any other ideas?
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