Fuel / Carb / Rough Idle Issue

[BigOtis]

Hey Guys, good Morning! I have a question that I know could be a million things but here goes anyway. I have a 1997 Regal with a 3.0L LX Mercruiser engine. Almost every maintenance item on this motor has been replaced in the last year. The boat has ran good through last year. I De-winterized it and launched it for the first time this year this past weekend. The boat ran ok from the launch to my destination and when I backed off the throttle the engine died. Now it only idles speratically or not at all, when I do get it idling I can go full throttle and it runs great until I back off the throttle then it dies again and the process starts all over. This engine has a newly re-built carb on it from last year. It probably has not had 20 hours on it. Fuel tank was filled for winterizing and fuel stabilizer has always been added in every tank. Any suggestions on where to start in running down this problem? You guys are great and thanks for any help and suggestions.

Otis

 

[Fishermark]

Do you have a water separating filter installed? Sounds like you have picked up some water or other junk. If you do not have a water filter, then install one. If you do, dump the contents into a clear jar and see what you have. Then you will need to remove the top of the carb and look into the fuel bowl and see if you have water / debris.

 

[BigOtis]

Fish, yes I do have a fuel / water separator system put in. That was one of the first things I done after buying the boat. I also, run the test you suggested yesterday. The fuel looked nice and clean. So it must be something with the carb? If so, do you suggest another re-build or is there something I can do with the carb to clean it up?

 

[BigOtis]

Is it likely I would need another carb re-build for the above scenario after it was just rebuilt one year ago? If so, how difficult is it to rebuild these Mer-carbs?

 

[Fishermark]

It may or may not need a complete rebuild, but it does sound like something has gummed up the idle circuit. It is pretty easy to separate the upper chamber of the carb and look at the fuel bowl and see what's going on inside.