'73 - 65 HP Merc losing power

[c3po]

This old mercury starts great, runs great, for maybe 10 minutes at a time. It does seem to have a knocking noise idleing. Runs good in the barrel. But when I get it in the water, make a short loop, it will sometimes die, or just slow down to almost planing. Worn out? Powerpack? coil?

 

[emckelvy]

Re: '73 - 65 HP Merc losing power

How's the water circulation and the engine compression?

 

[c3po]

Re: '73 - 65 HP Merc losing power

The pee hole is open and spraying out the exaust. As fo the compression, I will go borrow a gauge today and check it. How can I tell if the water circulation is good enough?

 

[c3po]

Re: '73 - 65 HP Merc losing power

Good news! I noticed the bottom carb was flooding, took it apart and found that I had put the float arms in upside down. We ran it wide open for 30 minutes or more today. No problem. But it doesn't jump out of the water like I think it should. I wouldn't attempt to ski behind it. Does anybody have ideas for me to try?