merc 50hp carbs.

[lotty123]

Hi guys, Have just got my first boat and it has a Merc. 50hp brownband. Have been having problems with it running roughly and lack of power. I know the boat has been out of water for about a year, the previous owner had it running with a set of mufflers on it pumping fresh water through it and it ran very well on the quay. Since I have refloated her and tried out he engine it seems as though it does not want to rev in gear. It does not have a tacho fitted but I guess she's not revving past 3,000rpm although in neutral she revs quite alot higher. I have noticed when priming for use that petrol does spill out from under the engine covers and am guessing she needs a carb rebuild. Does anyone have any other ideas to my problem? many thanks........

 

[rickdb1boat]

Re: merc 50hp carbs.

lotty123 <br /><br />You hit the nail on the head! You need to clean and rebuild the carbs to clear up your problems. DO NOT rev the engine in neutral above fast idle. You are risking a chance of your engine blowing up!! Odds are your float needles are gunked up, Sticking open and causing the fuel flow out of the carbs. Jets are also probably clogged as well. Clean and rebuild...

 

[andrewkafp]

Re: merc 50hp carbs.

Also, <br /><br />Always use fresh fuel.. and don't let stored fuel sit for any longer than a few weeks unless it has stabiliser added. This is a major cause of gunk in carbs.

 

[lotty123]

Re: merc 50hp carbs.

Thanks for the advice, I have one question, why should the engine blow up when revving in neutral? I am a fully qualified truck technician so deal with engines all day but have never heard of an engine blowing up in neutral unless it is revved really hard. I also race a 2 stroke motorcrosser and again have not heard of this, I am new to the boating world so do not know a great deal about outboards but have not seen anything on my motor that is vastly different from my bike engine. If there is something I am missing I would like to be put right to prevent damage. MANY THANKS......

 

[mellowyellow]

Re: merc 50hp carbs.

because if it runs lean, with no lube at high<br />revs.....

 

[rickdb1boat]

Re: merc 50hp carbs.

I guess I would have to ask what good is it to rev it to 5 Grand in Neutral? Any purpose served by doing that other than floating the bearing, pistons, rings and such and having a possible runaway condition that you can't stop until it self-destructs? Is this some troubleshooting technique I haven't heard off? Enlighten me!

 

[Clams Canino]

Re: merc 50hp carbs.

Unlike a geared motor these things were designed to run under one fairly constant load. When you take one (particularly multi-cylinder) up there with no load everything "floats" and stuff breaks, trust us, we've seen it. <br /><br />Fast idle is 1500, at no time should you break 2000 with no load.<br /><br />-W

 

[lotty123]

Re: merc 50hp carbs.

Thanks guys it all makes pretty good sense and will not rev this thing up in neutral.