Blower Idle Problem

I have a 95 Moomba boomerang direct drive and it will run fine when pulling or going faster than idle, but when I slow down and stay at idle for a long time (no wake zones) the engine starts to run rough. To get it to run better, I have to lift the hatch and let the engine breath. After that it will run fine untill it gets stuffed up again. Any ideas on fixing this? I have 3 vents in the back, but only one is blowing anything. Would buying another in-line blower and adding it to the back help or would that take to much air from the engine compartment?

Your carb is starting to percolate, probably. The cause could be the float is sinking so it does this easier. That fix is rebuilding or replacing the carb. The cause could be a lack of ventilation and another blower would help but before you spend those dollars check the air intakes. If you've done any interior work they could have been blocked or maybe full of leaves, or anything.
cold air at the fuel pump if it's on the block, the carb, and into the compartment will fix it more easily than drawing out air with a fan.

If it's percolating it will run rough and may stumble when you try to get on throttle.

It could also be the condensor, or coil, or lots of other stuff...

How would I get cold air to the fuel pump? Put a blower reversed sucking in air at the front vents?

I just replaced the coil, spark plugs, distributor cap, and had the carburator rebuilt. Like I said, it only happens at idle and it stops a couple of seconds after I open the lid.

It's definitely heat in the engine compartment then. The two grills on the bow of your Moomba are probably the intake air points. (I'm not familiar with your boat. I just looked at the picture on your profile.)
From each of those there should be a large 3" or 4" line that runs down to the floor and into the engine compartment. If those lines are not there, or are blocked, you won't be getting cold air in. If they are and they're open you should be getting lots of air in and you've got to check the exits. You said there are three. Check that each is open and not blocked by upolstery, sacks, or anything. There might be large lines going to the exits similar to the intakes.
If you need to extend one of the lines to blow up at the fuel areas of the engine.
If all else fails you can get a heatshield carb plate or an insulator gasket for under the carb from a speed shop.

When you are moving the vents should move much more air than any blower can.

(Message edited by rallyart on March 26, 2007)

I looked in the back at my blower, there are three vents in the back but only one, the one that has been blowing, has a tube hooked to it. I never found where that line went to or if it was clogged. I guess I'm going to start and check the lines and see if there is any blockage and go from there.

If you had all that work done in addition to checking the compartment air intake I would check the spark arrestor (air breather on top of the carb) and make sure tehe carb idle air adjustment is correct. If this only started after setting awhile and following all of that work you should be able to correct without any additonal parts.