79' mercury 70hp loses power

[jd33333333]

I just bought a 79' mercury 70hp 3cyl outboard on a 79' hydrostream vandal. I only paid $600 for everything and have put about $400 into repairs. I have taken it out about 5 times this summer and it had a lot of fun. It cranks up right off every time with no complication, but for the first 10 mins, it has no power... it wont reach planing speed. After about 10 mins of steady driving (very slowly), it will just burst with power and take off... without warning. This doesnt bother me so much.. but after an hour or two of skiing and cruising, it will suddenly lose power completely. I will turn it off and back on, rev it up a little in neutral, and wait a minute or two, and then it is back to normal at full power! It runs perfect 90% of the time. Also, it was sitting in a field for a year or two before I bought it... maybe the carb is gummed up? I did a compression check and it reads 132-127-130, so I dont think this is the problem. Also, there is a little bit of water that comes out of the spark plug holes when running... This doesnt look good (and probably isnt) but my local boat repair shop told me that it isnt a big deal on that old of a motor and not to worry about it... Can anyone tell me what I should do? <br /><br />I was thinking along these lines:<br />cleaning the carb<br />replacing the spark plugs<br />re-sealing the spark plug head<br />replacing the stator?

 

[Chris1956]

Re: 79' mercury 70hp loses power

It sounds like you are fouling a plug, likely on the bottom cylinder. When it looses power, pull the plugs and compare them. If one(or more) is very clean (like new), it is likely water in the cylinder "steam cleaning" the plug. If one or more are wet and oily(fouled), it is likely your carb needs cleaning and rebuilding (gaskets, foat height and needle+seat). <br /><br />You may also want to check for spark at those times when it looses power. Use an inductive timing light to assure that you have spark on all.