My friend and I own the same year 2004 Mercury 150 XR6 carbuerated motors and we are both experiencing the same problem. Motor starts great, runs great, idles great in the beginning and when you go to put it back on trailer it idles very slow and stalls.

Another Mercury mechanic advised Quickleen in the gas, new plugs and switching oil to Quicksilver Premium Plus to eliminate oil deposits on the plugs and cylinders. I'm thinking of bumping the idle up some but am unsure how to do that.

I'm not a boat mechanic, but engine is engine, right?!

I would start with the gasoline. How old is it? Was it stored over the winter, etc...? Perhaps just replace the gas. Check fuel lines for any damage. A carburetor cleaning additive might be a good option.

Further check the spark plug(s) and replace if necessary;

http://www.camaro5.com/forums/attach...1&d=1333331080

If that all doesn't help you might want to get the carb re-adjusted at a reputable shop.

Edit:

An oil change won't hurt, especially if it comes out of storage.

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Jorge

Having owned many outboards in my day. Big small all makes it is either Mechanical, electrical or fuel.

All the ones I owned had stators and power packs. Replace all them. Still had problems, clean. replace carbs. Still problems.

Buy new engine

Sorry.I do not miss those days.

Probably junky fuel with methanol. I would start with new fuel and a additive. Carb cleaning. Jets are gummed up.

Impossible to say these days as they are all high tech and need a computer.

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Still Running Against the Wind

Drained tank last winter so no bad gas. Refilled with new Hi-Test gas in April. I'll try the new plugs, new premium plus oil and the Quickleen to the gas.

Drained the tank, but did you drain the carb? They gum up very easily with today's fuels when they sit for long periods of time.

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-Roger

If I owned a junkyard. That Topaz we owned ran us into the poorhouse.

My boat mechanic says "Un-bolt it from the transom and replace with an OMC"

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sticks-n-stones&hollowpoints

CARBURETOR mechanic for 40 years. Most boats have a bowl with rubber gaskets u can remove & run a fine wire through the jets & idle passages. Setting is what does this. Long as it doesn't flood this should work. Spray cleaner in the passages & it should come out in a different place. There will be a blockage when the fluid don't come out.

Pay attention to 4 barrels post. If I'm not mistaken your motors are two cycle engines and the carbs on 2 cycles are prone to jets getting clogged over time. When that happens you get a lean mixture at idle and if it leans the carb out enough you'll end up with burned pistons.

Keys to maintanance is using a high quality oil EVERY time and it's also a good idea to have the carbs broken down and fully cleaned at least every 3 years. Yeah, it's serious money if you pay someone to do the work but it sure beats buying a new short block.