Merc 115 won't rev

[Grog]

My wife inherited a 19' Arima fishing boat with a 1991 or 1992 115 merc inline 4 cylinder on it. The motor has about 100hrs on it. It has sat for years. It seems to idle ok, but it isn't making any power. It only revs to 2900 rpm with the stock prop and won't get the boat up on a plane. I am going to try new spark plugs and a fuel filter. I am new to outboards, but I have been working with 2 stroke motorcycles for years. <br />Any ideas? Any information on this engine would be helpful

 

[sho305]

Re: Merc 115 won't rev

Do a serious check on the whole fuel system from tank to block. Any gummy fuel will cause problems. Clean the carbs/filters/tank/lines and throw some plugs in there and you will likely be good to go. Also check plug wires and cap if any, and it is good idea to put dielectric grease on them to help water proof them. Also makes wires come off plugs easy and seems to help them live longer and not crack. Check fuel pump for flow if you can, on mine it was quite cheap to just put new diaphrams in them and not have to worry about it.