1995 Mercury 115HP

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1995 18' Astro F&S w/ 115 Merc. Owned 2 years. Max speed 52MPH @ 5200 RPM. This year I seem to have lost 10 MPH and about 300 RPM. Max is now 42MPH @ 4750 RPM. Sea Foam in tank and new plugs, no help. Compression is 155lbs on top 3 cylinders and just shy of 150 on bottom cylinder. Pulled plug wires, got good arc but also shocked me through the wire. Any help would be greatly appreciated.<br />Thanks,<br />Mike

 

[dogsdad]

Re: 1995 Mercury 115HP

Well...what could change over a season?<br /><br />I suppose if you left your boat in the water over an extended period of time, you could have biomatter clinging to the bottom of your boat, and slowing it down.<br /><br />Or, maybe some critters have built a nest in the vicinity of your carburetors/intake??<br /><br />I guess you could simply have bad gasoline too.<br /><br />Also, you could have weak spark. It's much tougher for the plug to fire under compression than it is in the open air. If the wires are old, the insulation could break down under high loads and arc.<br /><br />One other thought---is your throttle control opening up the carbs all the way?<br /><br />Hope it's something simple!<br /><br />-dd-