1997 SN carb question
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=2183
Printed Date: November-23-2024 at 12:26am
Topic: 1997 SN carb question
Posted By: AUskier
Subject: 1997 SN carb question
Date Posted: August-02-2005 at 6:01am
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.
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Replies:
Posted By: Jim_In_Houston
Date Posted: August-02-2005 at 12:21pm
Sounds like the carb may be loading up (dripping into the venturi). I would rebuild the carb. Be sure to replace the needle valve and seat during the rebuild.
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Happy owner of a '66 and a '68 Mustang
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Posted By: David F
Date Posted: August-02-2005 at 12:26pm
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.
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Posted By: GottaSki
Date Posted: August-02-2005 at 12:46pm
Both diagnosis sounds right on. Drippy venturies is likely, and that means bad needle & seats and/or blown power valve.
Shutting down the air screws removes the air, but not the fuel...
The air screws should have been more effective ..also perhaps the secondary plates are hanging up just a crack...the push rod should be bent to force them closed when on the idle stop; but if the idle is cranked like Davis suspects, this linkage goes limp.
Sounds like multiple circuits are all boogered up, in more technical terms.
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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Posted By: AUskier
Date Posted: August-02-2005 at 9:46pm
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.
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Posted By: GottaSki
Date Posted: August-03-2005 at 12:30am
Cool, thanks. yup, water is magic
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole
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