merc 115 surging at idle

[izu]

I have a short video clip 1.5 mg that may help knowledgeable person id my problem.(exchange email address's). Otherwise I can only guess. Can a weak water pump cause this condition CLICK ON PHOTO..

 

[Chris1956]

Re: merc 115 surging at idle

Surging is usually caused by an air leak in the intake side. Are the carb base gaskets good? Are the carb mounting bolts tight?