Fuel leak at carb
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=19485
Printed Date: April-29-2024 at 10:35am
Topic: Fuel leak at carb
Posted By: OverMyHead
Subject: Fuel leak at carb
Date Posted: September-17-2010 at 5:11am
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I have a stubborn leak at the fuel fitting that enters the carb. Have tried tightening it multiple times but still get a small puddle on the manifold. Obviously not an acceptable condition. Can I use teflon tape or any other product on it? ------------- For thousands of years men have felt the irresistible urge to go to sea, and many of them died. Things got better after they invented boats. 1987 Ski Nautique |
Replies:
Posted By: Morfoot
Date Posted: September-17-2010 at 9:05am
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I'd remove the fitting from the carb and make sure that the threads are clean and free from debris. Look at end of the tube to be sure it isn't cracked. Replace it if it is. You might have some old teflon tape on the fitting or in the base of the carb so clean up both and put some new teflon tape on the fitting and tighten it up. Leak check it again to be sure yo fixed it. ------------- "Morfoot; He can ski. He can wakeboard.He can cook chicken.He can create his own self-named beverage, & can also apparently fly. A man of many talents."72 Mustang "Kermit",88 SN Miss Scarlett, 99 SN "Sherman" |
Posted By: GottaSki
Date Posted: September-17-2010 at 9:22am
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No, no tape.
Get a new metal gasket or fuel line if tightening doesn't work. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: 8122pbrainard
Date Posted: September-17-2010 at 9:22am
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Dave,
That flare needs to be double wrenched when tightening. It's a real tight area and on my Tique (had the same issue) I had to remove the throttle cable bracket to get to it. The problem is when it's tightened, you put a slight twist in the steel line and then the steel line will go back to it's original position unscrewing the flare adaptor. Loosen the flare first. Make sure the fiber sealing washer under the adaptor is in good shape. Tighten the adaptor and then double wrench the flare tightening it making sure you're not twisting the fuel line. A old trick is to use some lubricant under the flare nut (NOT on the flare itself) so the tubing will be free to rotate slightly until the flare is fully seated/tightened. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 81nautique
Date Posted: September-17-2010 at 9:38am
Exactly, the leak is probably not the flare fitting but the carb fitting with the screen in it. Replace the gasket and install this fitting tight then re-install your fuel line and see what happens. If that doesn't work replace the steel line itself. Pete suggested a while back to put a little grease on the flare fitting so the steel line can swivel as you're tightening, otherwise the line gets torqued and always wants to back off..Brilliant PS. chased this exact problem this summer and replaced both gasket and line to get it to stop. ------------- |
GottaSki wrote:Posted By: behindpropeller
Date Posted: September-17-2010 at 9:54am
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Posted By: Morfoot
Date Posted: September-17-2010 at 10:09am
If the fitting screwed into Carb is still leaking even with a new gasket then why is using Teflon tape a no-no? Pardon my stupidity and misleading suggestion. Maybe I should just stick to turbine engines  ------------- "Morfoot; He can ski. He can wakeboard.He can cook chicken.He can create his own self-named beverage, & can also apparently fly. A man of many talents."72 Mustang "Kermit",88 SN Miss Scarlett, 99 SN "Sherman" |
Posted By: 8122pbrainard
Date Posted: September-17-2010 at 10:15am
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Tim,
If all else failed, I'd be putting teflon tape on it too!  Really, the carb adapter needs to be tightened down and stay tightened. With the teflon and it's lubricity, I'd worry about the fitting loosening up. The new flat gasket should do it.------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 81nautique
Date Posted: September-17-2010 at 11:14am
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Best thing I've found to get that flare adapter tight is to get the fuel line out of the way and use a thin wall socket on it. Most other wrenches are just too bulky to get on it. Then go back and install the fuel line with the lube of choice and double wrenches. ------------- |
Posted By: OverMyHead
Date Posted: September-17-2010 at 11:59am
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I do not recal seeing the fiber gasket when I dissasembled the fitting. Can I pick that up at NAPA? or is it marine specific? ------------- For thousands of years men have felt the irresistible urge to go to sea, and many of them died. Things got better after they invented boats. 1987 Ski Nautique |
Posted By: 8122pbrainard
Date Posted: September-17-2010 at 12:04pm
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Dave,
You should be able to get it at Napa. As long as you're getting into the adapter, take it off and check the condition of the filter/screen under it. You may also want to take the adapter with you to Napa when you go for the sealing washer. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: GottaSki
Date Posted: September-17-2010 at 12:05pm
Because in these cases, the threads are not meant the sealing surface, like in pipe threads. Not on the adapter to carb body, nor the adapter to fuel line. Just an oppertunity for shredded tape to clog a jet or idle passage, or boogar up the needle and seat. And, I remember the gasket being a soft metal, not fiber. I concur, the two-wrench method is critical. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Bri892001
Date Posted: September-17-2010 at 1:08pm
I believe this is what you speak of: http://www.skidim.com/prodinfo.asp?number=RN0032 - GASKT FUEL INLET FITTING HOLLEY The part description even mentions it's a potential source of a leak. If it works it will probably be the best $1.39 you ever spend 
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Posted By: 81nautique
Date Posted: September-17-2010 at 1:09pm
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the gasket is metal and you may have to order it from Summit, none of my local autoparts stores could get it unless I wanted to buy a complete rebuild kit.
http://www.summitracing.com/parts/HLY-108-8/ - gasket Edit : whoa, beat me to it and much cheaper! but yes that's the right part. ------------- |
Posted By: Randy_in_Ohio
Date Posted: September-17-2010 at 7:31pm
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I've had this same issue on and off since I got my boat. I had Eric tighten it down when he had the boat last year and it was fine until the last time I took it out and noticed it was leaking again. I was able to tighten it up enough to get me through the day, but I'm always checking for a gas leak there. I have replaced the fuel line and the gasket. I was planning on rebuilding the carb this winter and figured I would get it sorted out then but I may take a look at it tonight over a couple brews. I may hit the lake tomorrow and I want to make sure this thing isn't leaking. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1602&yrstart=1991&yrend=1995" rel="nofollow - 1993 Sport Nautique |
Posted By: OverMyHead
Date Posted: September-17-2010 at 7:52pm
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Noi Luck at NAPA but they recommende the carb shop. The palce must be good . they had a bout 15 carbs on their front desk and at least 100 in site. The guy new thae carbs and sold me on each of the two size seals that tehy use on the intake for a $1.25 each. Said he would rebuild the carb for about $190. I told him I had an issue with the low spped mis screws. He said they get messed up but as long as it idles ok dont mess with it. So I hope I will be good for now. ------------- For thousands of years men have felt the irresistible urge to go to sea, and many of them died. Things got better after they invented boats. 1987 Ski Nautique |
Posted By: 8122pbrainard
Date Posted: September-17-2010 at 8:58pm
Dave, Must be a different carb shop. I've dealt with http://www.thecarburetorshop.com/Carbshop_carbs.htm - this place on a couple occasions. Once was looking for the Zenith T3X carb for my old 1927 Universal I rebuilt. He was the guy that said he had several but wanted $1600 for one rebuilt!  The other time was to get a rebuild kit for the carb I did use for the engine that came off a Wisconsin 4 cylinder industrial.
Glad you found the sealing washer as well as the other gaskets. Keep us informed on how the project of stopping the leak goes. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: OverMyHead
Date Posted: September-17-2010 at 11:09pm
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Pete, different place. This was in St Paul MN. Put in the new metal ring, cranked the flare adapter prety tight, then lubed the outside of the flare and tighend that fitting . Ran on the hose for about 5 minutes with no leak. will continue to watch. Thanks everyone. ------------- For thousands of years men have felt the irresistible urge to go to sea, and many of them died. Things got better after they invented boats. 1987 Ski Nautique |
Posted By: Randy_in_Ohio
Date Posted: September-20-2010 at 1:34pm
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I never got to go to the lake this weekend but I do think I put a stop to this leak once and for all. Using a 1" socket to tighten down that adapter was key. Pete's tip using the grease on the flange fitting was brilliant as well. I ran it in the driveway for about ten minutes and no leak!
One thing I would add is that after you have tightened down that adapter with the 1" socket and you are reattaching the fuel line, get both ends of the fuel line attached but not tight, then tighten them down alternating between both ends until tight. Be sure that both ends are well seated before final tightening. Big thanks to Alan and Pete.  ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1602&yrstart=1991&yrend=1995" rel="nofollow - 1993 Sport Nautique |
Posted By: Keeganino
Date Posted: September-20-2010 at 2:09pm
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Good thread. I had the same problem when I got my motor back from the mechanic- go figure. Luckily all I had to do was take the metal gasket out, clean all the surfaces and it sealed right up. Have been keeping an eye on it and have not had any leaks since. ------------- "working on these old boats may not be cost effective but as it shows its what it brings into your life that matters" -Roger http://www.correctcraftfan.com/diaries/details.asp?ID=4897" rel="nofollow - 1973 Skier |
Posted By: 8122pbrainard
Date Posted: September-20-2010 at 2:24pm
Randy, I'm glad it worked and happy to help out. Yes, aligning a hard flared line on both ends can be a challenge and I almost mentioned it in my grease under the nut post. The ends never seem to line up and care must be used to avoid cross threading the flare nuts. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: skyhawkflyer
Date Posted: September-22-2010 at 3:52pm
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Been there several years ago and fixed it... Here's how!
Remove the line, remove the fitting. Clean up the fitting well, mix up a small amount of Liquid Steel epoxy and apply to the threads and a dab on the thin washer. Screw it in and tighten it with a 1" 12 point socket and rachet. Let it cure, then reinstall your fuel line using pipe thread sealant (not the teflon tape) No more leaks, and it won't loosen up on you. Others may argue not to do this, however once installed you should never have to remove this fitting, even when overhauling the carb, there are no filters under it. Since I did mine I haven't had the problem of it leaking again and presenting an explosion hazard when I'm out skiing. |
Posted By: 8122pbrainard
Date Posted: September-22-2010 at 4:10pm
Thread sealant, liquid steel and no filter screen behind the flare adapter? Sorry but this is just poor advice. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 82 Nautique 1
Date Posted: September-22-2010 at 4:23pm
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Pete,
I agree. Why jury rig something that could and should be done right ? Not worth the risk. Buy the parts, fix it right, it is a Nautique. ------------- Original Owner " Dennis" http://www.correctcraftfan.com/diaries/details.asp?ID=4855" rel="nofollow - 1982 Nautique |
Posted By: behindpropeller
Date Posted: September-22-2010 at 4:25pm
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Posted By: skyhawkflyer
Date Posted: September-23-2010 at 2:28pm
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My 4160 just has a line adapter to the carburator, no filter underneath it, so no need to ever remove(I have a huge external water seperator/filter assy). I should have added that I was using a new line, washer, and adapter in an attempt to repair the leak permanently before a fire broke out. The new parts also leaked, and several of us came up with the JB Weld idea simply because in my application there is no need to ever remove it, this won't work for all as some carbs do have a filter.
I knew somebody wouldn't like this idea, but hey it worked very well for my setup, and it's been holding for almost 2 years now without leaks. |
Posted By: 8122pbrainard
Date Posted: September-23-2010 at 4:00pm
The external fuel filters separators have been used since the 80's. Keep a eye on it since I have a feeling your gas isn't the greatest in your location.
Someone took the filter screenout of your carb!!!!! 
The fitting pictured on the right shows it. I suggest getting it back in there. Good luck getting the epoxy busted loose. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: skyhawkflyer
Date Posted: September-23-2010 at 5:38pm
| Nope, I ordered a replacement and a identical part came in. I'm leaving it as is, no leaks and it works great. I also use a filter funnel when fueling and haven't had a problem since I bought the boat in 1993. Mine is not like the picture. |
Posted By: Randy_in_Ohio
Date Posted: September-23-2010 at 9:41pm
Are you sure? I have a 93 with the Holly 4160 and there is a screen in that adapter. It's kinda in the middle of the adapter, I didn't notice it the last time I had it apart, but noticed it when I had it apart last week. Mine was clean, but still not a bad thing to check. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1602&yrstart=1991&yrend=1995" rel="nofollow - 1993 Sport Nautique |
Posted By: john33617
Date Posted: September-23-2010 at 10:00pm
| the problem is the steel line it keeps pressure on the fitting , JB weld the fitting in place , replace the steel line with a USCG hose , barb fittings on fuel pump and carb |
Posted By: 8122pbrainard
Date Posted: September-23-2010 at 11:01pm
Sorry John but you also are giving out bad advice. JB welding is not how a flare fitting is designed to work. You also need to review the USCG regs on plumbing on the high pressure side between the pump and carb. Barbed fittings? Maybe you could get away with the hose if you drilled more holes in the choke plate? 
When are we going to see some pictures of your boat and engine? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: john33617
Date Posted: September-24-2010 at 10:09am
| the threads in the bowl are very fine and weak , heating and cooling of the engine puts pressure on them , thats why so many have leaks there , vibration and twisting also |
Posted By: skyhawkflyer
Date Posted: September-24-2010 at 10:22am
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Oh brother, you have got to be kidding me...
There is more than one way to fix this problem and it is NOT high pressure fuel. The pump maybe puts out 14 psi, but I doubt it. First of all, I always use clean fuel, so I've never seen rusted up fittings like you have posted pictures to. If you dump dirty fuel in the tank then I can certainly see your need to pull that filter every month or so. I vaguely remember a fine mesh screen as described however at my last carb overhaul 3 years ago it was perfectly clean. I keep my fuel clean and that eliminates about 90% of problems in itself. It's a poor design and it is a problem that keeps rearing it's ugly head. Buying new parts does not always solve the problem, and doing so doesn't permanently fix it either so I think you are giving bad advise as well. JB Welding an adapter in place doesn't destroy a carburator either. a safety wire hole could be drilled to secure it too. I have seen people struggle with this setup until the copper line gets over torgued and the flare cracks and then the boat is unusable. You just don't keep smoking it down tight with two wrenches. I have used the pipe thread sealant which I know you think is a pretty stupid idea, but it seals the threads (if the flair is leaking) and it also has a bonding agent in it that sets up so it doesn't loosen from vibration, yet it doesn't have the teflon tape shreds to foul the carburator. I know, it's a really dumb idea... |
Posted By: 8122pbrainard
Date Posted: September-24-2010 at 11:09am
John, Fine threads are weak?? The zinc alloy of the carb body may not have the tensile strength of steels but that's why it's tapped with fine threads! You're off in a direction that you shouldn't be since you have no background to back it up!! Again!!! Tell me, why are fine threads used on demanding high strength loads such as connecting rod caps!!!??? Tell me why SAE torque spec's are higher for fine threads than coarse threads!!!??? Do you buy JB Weld in bulk? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 82 Nautique 1
Date Posted: September-24-2010 at 11:34am
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If vibration is that bad, may want to check the prop shaft :)
I have owned my Nautique for 29 years and have yet to have the fitting vibrate loose. Guess I am the lucky one. I would find the answer to my problems causing the leak and again fix it correctly instead of patching it with JB weld  ------------- Original Owner " Dennis" http://www.correctcraftfan.com/diaries/details.asp?ID=4855" rel="nofollow - 1982 Nautique |
Posted By: Randy_in_Ohio
Date Posted: September-24-2010 at 11:50am
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As much as I love JB weld, and I find new uses for it all the time, I would never use it on my boats carburetor and fuel line. Seems really half-assed to me. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1602&yrstart=1991&yrend=1995" rel="nofollow - 1993 Sport Nautique |
Posted By: skyhawkflyer
Date Posted: September-24-2010 at 12:04pm
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Actually John is correct. The threads are weak because they are a poor fit, loose tolerance with the adapter. If the threads on the bowl were manufactured to the precision standard of connecting rod cap bolts then there probably wouldn't be an issue. There is no comparison here. And I certainly would not use a higher torque on the adapter just because it has fine threads.
SAE torques are higher for fine thread as these are generally manufactured as a high(er) strength fastener. Course thread fasteners are generally low torque, although they can be purchased in grade 5 or grade 8, or can be purchased without a grade rating as well. No rocket science here. Not all boats have the same engines and setups, some experience this and others don't. And I was not using the JB Weld to stop a leak, I used it to coat the threads so the fitting doesn't loosen. |
Posted By: behindpropeller
Date Posted: September-24-2010 at 12:08pm
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Posted By: 8122pbrainard
Date Posted: September-24-2010 at 12:42pm
What class fit are they? H2,H3,H4? Have you measured? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: john33617
Date Posted: September-24-2010 at 12:59pm
| with the steel line in place after time the JB weld would crack and leak , with the hose the JB weld has held for years |
Posted By: skyhawkflyer
Date Posted: September-24-2010 at 1:11pm
| I could care less what class fit they are. Have you measured them? Let me know what you come up with. |
Posted By: john33617
Date Posted: September-24-2010 at 1:22pm
| http://www.fishtheclassic.net/forums/showthread.php?t=23711 |
Posted By: 8122pbrainard
Date Posted: September-24-2010 at 7:36pm
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John,
Thank's for the link. http://www.fishtheclassic.net/forums/showthread.php?t=23711 - John's link That fishing site forum does have some smart people on it that know how to handle the fuel lines from the pump to the carb. Here's a copy/paste: "Quote: Originally Posted by inetmug Hey Guys, I imagine the fuel line setup from the FP to the carb is supposed to be hard plumbed like in my old IO's. I hate to admit this but I just noticed the previous owner jury rigged it with standard CG fuel line to a barb fitting, most likely when they replaced the carb in '05. The line is not in danger of chaffing or near anything hot, but still it is not right I imagine. What is the proper setup for this, and can a steel braided line be used? I am told yes. My local Holly speed shop has SS brained line with alunimum fittings but they could not comment on ethanol with the lines, and since they all pump high octane stuff they do not see ethanol." Reply from Jimmy's marine service: "personally,i would never use that set up-i realize the cg states it's ok,but it doesn't pass my test... get the correct line to fit it-order it from the mfg of your engine. i've ran into this alot as well,owner's some times lack tools,they use a regular openend wrench on the fittings,round them off,instead of using the correct flare nut wrench...the "pre shaped" lines are available from crusader,mercruiser and pcm...use a dab of grease on the line then,slide the nut over it,this will avoid the nut siezing to the line..." ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |