Carb Rebuild 1991 SN - Please HELP |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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Posted: July-12-2018 at 9:02am |
I completed the carb rebuild yesterday and put her all back together. Long story short it is leaking fuel at the rear bowl. I rechecked gaskets and ensured the bowl was tight and it is. I am not sure what to look for, but any and all help is appreciated. There were several needle sets in the rebuild kit from SKIDIM, but they all looked the same. What am I missing guys?
Holley on 351 PCM - LIST 50469-1 (Number on horn or carb used to order kit) Thanks in advance!! Gary |
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10664 |
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Where at the rear bowl is it leaking from?
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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It appears to be from the bottom...
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10664 |
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That's not a lot of help
Sounds like it's time to pull the bowl off to get a better look at things like gaskets and the seals for the bowl screws. You're talking about an external leak onto the manifold right? You also have the transfer tube with an O ring that can get pinched and leak/spray gas but that's at the top |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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Yes external leak on to the manifold. I looked at the transfer tube and it is good. Both O rings in place. New Seals on all 4 bolts...
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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Update - A friend told me to see if I can spin the transfer tube with my hand. Just so happens that I can spin the transfer tube. So maybe it is the O Ring to the seondary as you suggested? Maybe it got pinched?
Gary |
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10664 |
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Not exactly many choices other than pull the bowl (the rear is relatively easy while the carburetor is on the engine) or pull the carburetor so you can get your eyes under it and see what's leaking.
Most every kit these days comes with reusable bowl gaskets so you should be able to reuse it as long as it isn't pinched, torn etc. Another obvious spot that's not on the bottom and easily visible would be the 2 welch type plugs, one on the side, one on the top of the bowl but I figure you'd have noticed if it were one of those. |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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Keno,
Yeah its not the plugs on the bowl. I am going to remove the transfer tube and inspect the O rings. I am guessing one is pinched as you suggested earlier. I can rotate the transfer tube by hand so its definitely loose. Also, I was at the key and by myself so I couldn't actually see it in real time, but it "appeared to be leaking from the bottom. If the O ring was pinched and fuel was pouring out of the bottom of the transfer tube on the back side, I am thinking it would run down and by the time I got back there to look it was dripping onto the manifold and looked like from the bowl. Does that make any sense at all? Also, it was A LOT of fuel which doesn't lean toward a "leak in the bowl gasket" but more like a blown seal at the tube. I will post back in a little while and let you know what I find on the O Ring. Gary |
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10664 |
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Sure sounds like the transfer tube.
If it is the tube, take a look at the thread in the link and there are pictures of the newer style tube that uses some better seals on the ends link Your kit may have come with those seals included and if it did you can make a new tube out of 1/4 inch brake line like in the linked thread. It's much harder to screw up the new style seals. |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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KENO - Ordered a new tube anyway from summit. Seems like a better application and for $10 how can you not right. So here is what I found. I took apart the rear bowl and needle assembly and found pieces of a blown O ring (the first one that got pinched last night and I replace it) in the needle assembly. I tried to upload a pic, but forum isn't cooperating.. Nonetheless since the needle assembly wasn't working I am assuming the bowl filed to capacity and fuel leaked at the weakest point it found - O Ring at transfer tube. Going to get some new O rings until the new tubes arrive. Will keep ya posted. Thanks for the help.
Gary |
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3333 |
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after assembly i always spin the xfer tube and push fore and aft to fully seat the o-rings.
In order to avert a leak so i don't see the connecttion that spinning = bad tube If its sealing surface is compromised, then thats a different matter |
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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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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10664 |
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Sounds like the needle valve was stuck open in which case the bowl will fill up and the leak path to make it an external leak is the bowl vent (J tube) which should direct the leakage down the secondary throttle bores but with fuel pump pressure and a good sized seat leak it'll spray a lot.
or do you mean the rear O ring was broken and you found it's parts in the needle and seat assembly? |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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Thanks. I got some new O rings and fixed the leak. I can't get it to start though. Probably fouled the plugs with over flooding. I checked them, and when I took one of them out fuel actually spilled out.
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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Sorry I didn't answer your question. - The front O ring was broken yesterday and I guess it sent some parts of it to the rear if that makes sense???
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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91NaughtyQ
Senior Member Joined: July-27-2015 Location: NC Status: Offline Points: 287 |
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UPDATE - Well I finally got it all sorted out. - Rebuild complete. I added some new spark plugs after and set the idle mixture screws to 1.5 turns and it runs like a champ. The boat has never run better. Thanks for all of the help. - In short, Carbs don't like trash in the bowls and new plugs make a huge difference when you have fouled the old ones from excessive flooding.
Gary |
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1991 Ski Nautique
(Previous)1984 Ski Nautique 2001 |
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