Boat wont idle...please help.

Hey guys, I need some help here. I am still having some problems with my boat after rebuilding the carbs. Here's the info:

When I put it away last fall, it was running great as always. After lubing everything, changing the oil/filter, etc. when I pulled it out into the driveway to fire it up, the carbs were leaking gas everywhere (maybe due to the extreme cold winter that we had, and my garage is not heated). I had both Holley 4150's rebuilt and the boat will run above 3000 rpm, but still won't idle. The engine is a 496 BBC that puts out 700+ hp. It has an electric fuel pump. I need to find out tomorrow if the guy that did the job used 30cc or 50cc accelerator pumps (it takes the 30cc pumps) and which gaskets he used, but if he did use the correct pumps and gaskets, I can't come up with why it won't idle. This guy is a more than competent motor guy that works for the best boat shop that we have here in the Boise area and has a lot of experience with boats like mine, so I'm confident that he has the carbs adjusted properly.

Any ideas? Please help so I can try and get this on the water before summer runs out! Thanks.

I'm no carb guru, but isn't the idle more metering vs accelerator pump?

Where was it leaking from?


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It was leaking from the floats, the throttle body, etc. I spoke to the shop today, and they can get it to continuously run at 3000 rpm and above, but as soon as they try to adjust it down, the boat dies. They're going to run a compression test on it, and are also wondering if a valve may be stuck open, and although I know engine basics, I'm just not sure where to go from here. Are there any solid boat techs here on the forums that could maybe point me in the right direction? Thanks.

What does a valve being hung open or a compression check have to do with the fuel bowls over filling?

Let's keep this really simple. Did you check the needle/seat o-ring?

No, the carbs are all good now. Completely rebuilding carbs is beyond my capability, so that's why I took it into the shop. Like I said, they can get it to consistently run at 3000 rpm and above, but whenever they try to bring it down anywhere near the 1200 rpm that its supposed to idle at, it just dies. Could it be an air leak, or it's just flooding out? And how would you know that it's flooding out? I know that the guy that rebuilt the carbs has worked on hundreds of boats like mine over the years, so I'm confident that he knows what he's doing, but again, here in the Boise area, we are limited to a small group that knows anything about high horsepower jet boats.

If the wrong base gaskets were used, could that affect it? Or does it sound like a metering problem?

It seriously sounds like a carb issue to me.


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