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brand new Mercury 9.9 with low compression and performance.

tgeers

tgeers

Member
I replaced my 1964 mercury 9.8 with a brand new four stroke Mercury 9.9. I followed the verbal and written break-in instructions to the letter, adding even more time to each phase of the break-in. It is on a 10 foot, tricked out with aluminum jon boat. After the break-in I checked the spark plugs, as recommended, did a compression check which came to only 60psi in each cylinder. It starts and sounds good, but I can't get it to run over 7 mph. Something is wrong, but what? Called the service center and they told me they could get see me in three weeks. I fish at least every other day. This is not acceptable. Can I do anything in the meantime?
 
I'm going to call the service manager today to see if I can bring it in and have them check the compression. That shouldn't take them more than a few minutes. (less time than it took me to fill out the paperwork to buy the motor). I'm sure you folks have dealt with outboard service people more than me. If you have some advice, I'm listening.
 
Took my motor in to the service manager. They tested the compression and said the problem was not with the motor but with my new compression tester. Go figure. Meanwhile, the best it will do is 6mph on calm water. It's a 10ft aluminum jon boat with a trolling motor, 3 gal fuel tank, me-180lbs, fishing tackle and 15lbs anchor. what's your opinion on performance? Am I expecting too much?
 
I've seen YouTube videos of guys with bigger boats than mine doing 18mph. All I need is 10mph. The service folks claim it was making 140psi on compression and that 6mph is about right for a 9.9. I'm going to take the motor to my auto mechanic and use his compression tester to verify service's reading. I spent $2400. on this motor and I want something that will be worth it. I don't know where to go from here. Hopefully someone on this forum has a suggestion.
Thanks guys for your help.
 
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