loss of power on 115hp merc

[j e hutchison1970]

ok, i bought this glastron 17.5ft. tri-hull with a 115hp merc 1970. the boat had set for 8 months when i got it then i put new fuel(50-1) and had the throtle and shift cable replaced. i took it out and it had lots of bottom end power and 42mph at full throtle 5500rpms. then the next time itook it out i lost my bottom end power and only 36mph top end at 5000rpms with new spark plugs. anyone have any suggestions?

 

[j e hutchison1970]

Re: loss of power on 115hp merc

also i found out that when i had all this power (42 mph top end) i was not mixing my fuel right, a little lean on the oil.i know, not so good but everything seems to be ok. could that give the motor more power?

 

[Spidybot]

Re: loss of power on 115hp merc

Theoretically, yes. In practise no - and no way in the range you mention.<br /><br />The low mix run most likely did no harm to your engine because you did not run a lot idle. When up and running higher rpm the fuel/oil amount supplied is much higher and provides better lube.<br /><br />Apart from that, I'd check the fuel supply. Sounds as if something is preventing the fuel from getting into the engine at sufficiemt amount when WOT.<br /><br />An engine sitting this long may need a thorough carb clean, but I'd suggest you try a cleaning additive before dismantling the thing.

 

[j e hutchison1970]

Re: loss of power on 115hp merc

hey, thanks for the help ill try a ney fuel line and check the tank.ive already installed a new fuel filter.<br />also when i got the boat it had a car electric fuel pump, i was told to removwe it and replace with a fuel ball.i did.<br />thanks again....

 

[Spidybot]

Re: loss of power on 115hp merc

As a rule auto electrics are NO GO for for marine use.<br /><br />Once primed the fuel pump on the motor sucks the fuel up from the tank. The hose itself doesn't block easily but it can happen (the inner tube collapses) as can the bulb valves act strange.<br /><br />I'm more concerned with all small passages inside the carbs (nozzles etc.) They can be hard to clean and this is why I suggest the cleaning additive. Sometimes nozzles cannot be cleaned and have to be replaced. No very expensive, but takes a dismantle and other serviceparts to do.

 

[j e hutchison1970]

Re: loss of power on 115hp merc

thanks again for the info, i'll give it a shot...