HELP PLEASE: 2000 Merc 200hp Saltwater, 2 stroke runs poorly at low speeds

[2000BaylinerTrophy]

Hello,

I purchased a Used 2000, Bayliner Trophy boat, 23' long this spring. The Engine is a 2000 Mercury 200HP, Saltwater, 2 stroke. It starts just fine, and idles ok, but when I put it in gear and run slowly, the entire boat shakes.

It shakes at trolling speeds of up to 8 or 9 mph, I give it a little more fuel and it smooths out. No issues running it at WOT, and it gets the boat up to about 40 mph. I thought that the fuel in the boat might be old (From the previous owner) so I syphoned out every last drop, and and put in 75 Gallons of Fresh, Ethanol Free, 87 Octane fuel.

The Engine has all new Spark Plugs, and a fresh fuel filter... I run QuickSilver 2 cycle engine oil, and the prop isn't bent.

Again, the Symptoms are engine shakes at slow speeds. It also seems to smoke quite a bit when going slow, but it is a 2 stroke engine so it may be normal (I just recently bought the boat).

Oh, one more thing I noticed. Water is not coming out of the upper outlet. Might this be a sign of the Impeller needing to be replaced?

 

[Dukedog]

Re: HELP PLEASE: 2000 Merc 200hp Saltwater, 2 stroke runs poorly at low speeds

Carburetors, efi? Idle rpm in gear?

 

[2000BaylinerTrophy]

Re: HELP PLEASE: 2000 Merc 200hp Saltwater, 2 stroke runs poorly at low speeds

Carburetors, efi? Idle rpm in gear?

Hello, this is the EFI version. Sadly I do not have a gauge to measure RPMs. But the engine shakes and smokes quite a bit from Idle up to maybe 1/4 throttle. Once I open it up, things smooth out.

Any thoughts?

 

[Dukedog]

Re: HELP PLEASE: 2000 Merc 200hp Saltwater, 2 stroke runs poorly at low speeds

Someone on here might have tha correct answer but......It could be several things and would suggest ya find a GOOD (that's tha trick) shop that can figure it out. Being tha 'lectronic motor it can get expensive really quick if ya miss it tha first time. could be anything from leakin' mechanical fuel pump to O-rings, injectors, tpi, ecu, timin', idle stabilizer and etc. A little tuff ta figure it out on a computer.

Don't understand "upper outlet"? It should have only one small discharge hole at tha bottom rear of tha cowl..........

 

[Big Fish Billy]

Re: HELP PLEASE: 2000 Merc 200hp Saltwater, 2 stroke runs poorly at low speeds

Could be as simple as plug wires....or incorrect timing....