5.7 Mercruiser runs rough when hot

[Tom Bell]

My 2000 5.7 Mercruiser idles and runs rough after running around the lake for several hours. Sometimes it runs better after cooling off for 20 minutes or so. Sometimes the problem comes back right away. I've changed water separating fuel filter and checked in-line screen filter. <br /><br />Help!

 

[akriverrat]

Re: 5.7 Mercruiser runs rough when hot

need more imformation. carb or efi? points or electronic? how hot? any noises? don't be afraid to give to much imfo.

 

[GA_Boater]

Tom, I am having the same problem with my one month old remanufactured Merc 260 5.7L. Once warm, it idles extremely rough, and starts to die out when attempting to drive / throttle up after warm up. What was the resolution? I have changed out my fuel/water separating filter as well as my inline filter at the carb. Still, no change. Boat only moves at idle, and barely at that. It's struggling hard. This began when throttling up after getting on plane and the motor
backfired once or twice. the tach rpm jumped around a bit as well. Any thoughts? ???

This may be a record. This thread is 12 years old and Tom made one post, never to be heard from again. So it's doubtful he will answer your question. Read the Help Tip on top of the page and start your own topic if you really want help.