My 02 240 EFI smokes like crazy @ idle and low speed. Oil consumption is
ok though. Is this an inherent problem w/this engine?

It's a 2 stroke so it's prone to some smoking, but the problem can be made MUCH worse by using non-Mercury oil and having fouled/worn/improperly gapped plugs.

I'm using Amsoil synthetic. The plugs are new and gapped properly. The smoking
condition is ridiculous. 10x worse than any other O/B motor I've owned.

Only the Amsoil Saber Outboard oil is TC-W3 rated. If you are using any other Amsoil product, I'd stop. I find that the Mercury Premium Plus 2-stroke oil works great for me and I can buy them in 2.5 gallon bottles for convenience.

This problem has absolutely nothing to due with the oil I'm using.

The TC-W3 rating (ashless 2-stroke oil) seems to work for the rest of us.

Amsoil HP injector oil is a TC-W3 oil.

Other than that, perhaps it's just running too rich at idle. what kind of story do the plugs tell?

What RPM does your 240 idle at? If your running under 1,000 RPM... that could be causing the smokin problem.
Rj

Idles @ 1100

Do you notice excess use of oil? When the 240's are new, the oil is set on the high side. I watched as our shop reset the oil setting. The mechanic used a mirror to view the set marks. "If you don't use a mirror... it is impossible to set properly", so he said. I bet your 240 is still running oil rich as it was for burn-in.
Rj

Oil consumption normal. Boat was just set up @ dealer.

What was the problem?

Low idle and warm up mine is smoking really bad. It's probably the worst coming into the dock after it's warmed up. Last time I took it out it fouled the plugs and I had to take each plug out and clean them to get it to run. It was really embarrasing. Any thoughts? It has been doing it since I bought it 2 years ago. I took it to Seadoo a while ago and said its just what these engines do. I heard that a Mercury shop is more qualified to fix it. Any advice is good.

Thanks

Do you run "Mercury Quickleen" or Seafoam in your fuel on a regular basis? It's important to do so, especially in:

1) Two stroke engines, and

2) Engines that idle a large percentage of their running time.

Two years ago I failed to use Seafoam or Quickleen regularly. The result was exactly what you describe: An increase of smoke and nasty fouled plugs. I'd clean the plugs and they'd foul again quickly. The smoke was bad, even though I use Mercury Premium Plus oil which is one of the least smoky available.

Research revealed that carbon deposits had built up in my engine. You can prevent them in the first place by running Quickleen or Seafoam regularly (I do so at least every other tankful now, and usually every tankful). But if you let it build up you must do what's known as a "decarbon" on your engine.

This involves running an extra-rich mixture of (usually) Seafoam through the engine. You set up a standalone outboard-style tank with some fresh fuel and several times the normal ratio of Seafoam. Hook this up to the engine in place of the normal tank, start the engine, and let the engine warm up normally. It will smoke like a chimney the whole time.

Once warm, run the engine at various RPM's for a few minutes, then shut down the engine and let it sit for a few minutes so the residual fuel/Seafoam mixture can loosen more deposits. Restart the engine and repeat the cycle. Do this for a while (we did it for at least an hour). Every time you start the engine the smoke will be unbelievable - a combination of the additives in the Seafoam and the carbon deposits getting burned off. Do this late some afternoon when everyone else is off the lake or they'll be either angry, or convinced your boat is on fire.

Take along the tools necessary to remove and clean your plugs. It's likely they'll get seriously fouled while all that crud gets loosened up in your cylinders and on your pistons.

When you're done, reconnect your normal fuel tank and run the engine until the smoking stops (to insure none of the ultra-rich mixture remains in the engine and fuel system). Remove, THOROUGHLY clean, and regap your plugs.

Your engine is now decarboned. Keep it that way by running either Quickleen (available from any authorized Mercury dealer that sells their oils, etc.) or Seafoam (WalMart, NAPA, auto parts stores, etc.) in at least every other tankful of fuel. In addition to keeping your engine decarboned, this also keeps your injectors clean so they can open and close properly, resulting in better mileage and smoother operation.

Do a Google search on "decarbon engine" for more info. Add the word "boat" if you want to narrow it down a bit.

Hope this helps!