1997 SN carb question

Hi I have a 1997 Ski Nautique with the Holley Carbureted 351 engine. Starts up pretty easy, idles well, and runs smooth. Strong all the way up. However, after an extended idle it will miss or hesitate and sometimes die when trying to pull a skier up. This does not happen if I do not idle for a long time or if I put it in neutral and rev the engine up before attempting to pull up the skier. I put new spark plugs and a fuel filter in. No change. I thought maybe it was running rich at idle because of some smoke and a gas smell in the exhaust and it is getting a black sooty residue each trip out; so I tried adjusting the idle jets on the front of the carb. I could go all the way in (lean) and idle did not change. I could hear a change in the carb but the engine continues to run at the same RPM. After leaving the screws all the way in the engine would die immediately when increasing the throttle. So I adjusted the screws back out in small increments trying each position along the way. I can get it to idle fine and run strong, but the problem of it missing after a long idle has persisted.

Any ideas? What should my next move be? Heck for all I know I could be barking up the wrong tree, I just assumed it was a carb problem. Thanks in advance.

Jim probably has it spot on. Odd that the engine did not die when the idle screws were fully seated. This tells me that the idle speed screw is adjusted to compensate for the clogged idle circuits and/or dripping venturies to keep her running. With a high idle, the idle circuits in the carb are by-passed. The mixtures screws on the carb are for the idle circuits.

It does indeed seem that the carb is due for a rebuild and thourough internal cleaning.

Thanks guys, Looks like I'll be ordering a kit from skidim. Not sure about the idle speed screw. I had backed it off myself (of course I would need a normal position to compare it to which I don't know) Right now it is idleing at about 600 to 650 rpm. I'll look at the secondary plates when I get a chance.

Any specific things I should know or look out for in rebuiding the carb? (I'm a pretty mechanical guy but I've never rebuilt a carb)

Gotta ski, I like your sig. Loved that book and movie as a kid. Grew up in a family that "messed" with boats. Our first ski boat was a 77 Ski Nautique. It was about the same age that I was. When I went to college my dad got a mastercraft and I've ribbed him eversince. This is the first boat I've owned personally and I'm glad to be messing with a Nautique. Didn't even look at anything else.

Great site. Thanks for all the info.