Need help with 1972 Mercury 7.5 hp

misfire

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Jul 14, 2002
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» Hello, misfire [ log out ] iboats Boating Forums   » General   » Outboard Engine Troubles & Questions   » No top end on 7.5 Mercury <br />    <br />Author Topic: No top end on 7.5 Mercury <br />misfire <br />First Mate <br />Member # 13089 <br /> posted July 15, 2002 02:49 PM                <br />Can someone please help me? I bought a used 1972 Mercury 75 (7.5 hp) which had set for several years. It looks like new, but I never could get it to run out. Took it to a repair shop and they went all through the fuel system. Still no top end. It starts on the first or second pull every time, but with 2 guys in my 12-ft. aluminum V-bottom, it barely moves along at full throttle. Someone told me it could be the stator. What does the stator do? A buddy has a 7.5 hp 50-year old Evinrude in original condition that will run circles around mine. Ditto with another friend's newer 6 hp Johnson. Anyone have any ideas?
 

Bear

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Mar 1, 2001
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Re: Need help with 1972 Mercury 7.5 hp

Shaft length? The anti cavitation plate should be level with the bottom of the boat.<br /><br />The prop? Is like new too? No sail boat high thrust low pitch propeller I hope.<br /><br />How will it perform if you are alone, no gear or heavy stuff in the boat?<br /><br />Do the carb open fully?<br /><br />What if you try one of your friends motors on your boat or your motor on their boats?<br /><br />I have two 12' boats, same weight.<br />One '66 Johnson 6HP wot 7 mph.<br />One '87 Mercury 8HP wot 20 mph.<br />If I move them to the other boat one would still do 7 mph and the old Johnson will do about 11-14 mph.<br />That is because of the hull shape.
 

misfire

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Re: Need help with 1972 Mercury 7.5 hp

Thanks, Bear<br />That is the most logical solution I have heard yet, about the shaft length. Soon as I can, I will try your suggestions and let you know how I come out. The 7.5 Evinrude pushes my boat right along. I have tried that. Can't try mine on his, because he doesn't have a boat. The Mercury runs about the same with no gear and me alone in the boat. The carb seems to be opening fully, so don't think that is it.
 
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