[kenner99]

I am looking to purchase a 99 kenner with a 90 Mercury engine. We took it out to test drive. It seems to have worked alright at first then would not accelerate above 4,000 unless you babied it up their. I had the shop pull the plugs and the upper plug is dry. The other two lower plugs look ok. The motor would smoke a little upon initial start up. But would have alittle trouble starting after a while. The compression for all three cylinders is ok. Could it just be that it needs the carbs cleaned up? I want to buy the boat but want to make sure that it is just the carbs. Any help would be greatly appreciated.

[kenner99]

The motor is a 1999 but the horsepower is 90. It also smelled a little rich upon start up and had been sitting for a few months.

[kenner99]

anyone?

[Silvertip]

A dry plug indicates no fuel which is a common cause of engine failure. With no fuel there is no oil either. Since that engine doesn't have a removeable cylinder head, I'd insist on a bore-scope check of the cylinder walls to check for scoring. Even though you said compression is ok, I would still be leery. Did you observe the compression test or did the seller just tell you it was ok?
If one carb is acting up, the other two are probably close to failure also. All three should be removed and rebuilt. A little smoke at startup is normal and the actual amount is determined by the type and brand of oil being used. Synthetic, semi-synthetic-and conventional are least smoke to most smoke respectively.