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1987 75 hp merc seems like I let off throttle but I didnt ??????

johninmo

New member
Hello I have a 87 75 horse merc. on a 16ft Hydra-Sports Bass Boat I just left the ramp this morning got up on plane and drove about 2 miles then all the sudden it felt/sounded like I just let off the throttle but I didnt it was all the way down we fished till noon or so but every time we would go to move we had to get on the front to get on plane once we got on plane we stayed up just no real speed at all any ideas??? I just wanted to add that it starts idles and runs good at low speeds just dont go any faster

Thank you
John
 
Re: 87 75 merc seems like I let off throttle but I didnt ??????

I tested my compression it was 130 in #1 140 #2 140 #3 and in an effort to test #4 i took of this cover in the pic and found this piece and this not inside in the next pic does anyone know where it goes and could this be the cause of my problem????? and do the compressions seem OK ?

Thanks
 
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Re: 87 75 merc seems like I let off throttle but I didnt ??????

Compression looks good. Your picture didn't post, but it sounds like you have a fuel problem, most likely gummed up carbs, or a stopped up fuel filter.
 
Re: 87 75 merc seems like I let off throttle but I didnt ??????

after further inspection of my plugs it seems there is a piece of metal(aluminum??) on the end of my #1 plug touching the electrode could this have been my problem all along?
progress.gif
 
Re: 87 75 merc seems like I let off throttle but I didnt ??????

It could be,, but I would be very concerned about where this metal came from. Possible piston failure?????
 
Re: 87 75 merc seems like I let off throttle but I didnt ??????

:eek: Not good metal on the plug.Do the compression on it ,I'm betting on 0 or very close to it.Sounds like a piston detonating.
 
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