2001 5.0L Merc Carb quits at idle

Hello crew,
We are the original owners of a 2001 Sea Ray 190BR with a carbureted 5.0L engine. The engine runs perfectly, except..... Often when you bring it back to idle, it instantly quits. It needs to sit for 5-10" before it will start. It will stumble when the starter is first engaged, but will not light off, until it has been off for a bit. Once it is running, perfect, and, no lag/delay, gets to WOT quickly. It will run when the throttle gets back to the starting detent, but at idle, snuff. I only run premium/ethanol free gas. I've always used Sea Foam, but have added two different additives trouble shooting this. Put a new fuel filter in (the oil filter sized one. If it had a fuel pump, I would think that was not producing enough pressure, but the carb versions do not have one, correct? Also, is there a different fuel filter? Open to all thoughts, I deploy in August, so only two weeks of summer with the kiddos left!!! Only 148 hours on the engine, many babies, little time Thanks in advance,
Steve

Re: 2001 5.0L Merc Carb quits at idle

First off...Thanks for your service Steve, and stay safe on your deployment. Been there.

Your carburated 5.0 does have a fuel pump. Follow the hard line that is attached to either the front or starboard side of your carb and it will lead you to the pump. There is another filter between the pump and the carb as well. If you disconnect the hard line from your carb, there should be a small filter in that cavity accompanied by a spring and gasket. It is a very fine filter that I personally prefer to check annually. The large filter you changed is a Fuel/Water separator element that does filter debris but not to as fine a partical as the small filter in the carb.

All that aside, it sounds to me like your float may not be closing the inlet needle completely and your carb is flooding at idle. Fuel additives and seafoam are good products but sometimes all the best precautions don't prevent a small piece of crud from getting into a place that gives you a problem. Do you smell fuel when it doesn't want to start???

Re: 2001 5.0L Merc Carb quits at idle

JJBoatr,
Appreciate your service, and the quick response! There is no fuel smell when it is difficult to start. I would guess that if I went out right now, it would start and idle. But after the first run, when you bring the throttle back to idle, it will most likely stop running.
V/r,
Steve

Re: 2001 5.0L Merc Carb quits at idle

Ok, so no fuel smell. The only other issue with the carb could be the idle air mixture is to lean. You should verify your ignition system is operating correctly before adjusting the carb. How old is your ignition coil? If your coil is on its way out it may be getting hot and killing your ignition until it cools off. Will the boat run at all when it does this?

Re: 2001 5.0L Merc Carb quits at idle

Negative, it will not run at all. Cranks and cranks, will not catch. Can sometimes turn the Run/Stop toggle on/off while cranking, it will stumble, but not catch. Wait 10', starts and purrs like a happy kitten. Took it to a boat dealer here, they could not duplicate.

Re: 2001 5.0L Merc Carb quits at idle

cobalt650 said:

Negative, it will not run at all. Cranks and cranks, will not catch. Can sometimes turn the Run/Stop toggle on/off while cranking, it will stumble, but not catch. Wait 10', starts and purrs like a happy kitten. Took it to a boat dealer here, they could not duplicate.

Click to expand...

Ayuh,... Welcome Aboard Steve, 'n a Big Thank You for yer service to Our Great country,...

Are ya Handy 'round motors at all,..??
Can ya Check for Spark when it won't start,..??

Has the Lower Shift Cable ever been replaced,..??
When was the last time the drive was Off for a service, 'n inspection,..??