Mercury 40 hp no power low rpm

Pluto

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Joined
Oct 5, 2003
Messages
7
I have a 1995 Mercury 40 hp 2 cyl. since new. This last 4th of july we used the engine after 2 years of storage. New gas and plugs were installed. Started great as usual, after 10 minutes of use I noticed that the engine was no longer holding iddle and it was bugging from low to midrange until 3/4 to full was obtained. After 3/4 of throttle the engine seems working fine.

Cleaned the sigle carb, no improvement. Did some trouble shooting with the engine running and the garden hose on. Pulled the lower plug cable , no change. Pulled the top plug cable, engine stalled. Pulled the lower plug out and ignition is evident and blue. Checked the ignition from both plugs at night time and they look to be working proper on both plugs.

I did a compresion test and obtained 120 on both plugs.

What could be the problem???

Thanks to all

Pedro
 

Laddies

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Joined
Sep 10, 2004
Messages
12,218
Re: Mercury 40 hp no power low rpm

Sounds like a ign. failure on 1 cyl. I it has spark when the starter is turning it over you will need to test it with a DVA to find the problem
 

Pluto

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Joined
Oct 5, 2003
Messages
7
Re: Mercury 40 hp no power low rpm

Thanks for the help. Aparently the lower plug has spark as the top one does. Sorry for my ignorance, DVA stands for????

Pedro
 

Pluto

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Joined
Oct 5, 2003
Messages
7
Re: Mercury 40 hp no power low rpm

Will it be posible to relate the problem to reed valves????

Pedro
 
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