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kjohnson
12-11-2012, 11:07 AM
I have a 91 PS 190 and had to disconect the metal fuel line where it connects to the carbureator. I have had a lot of trouble getting the connection tight enough so that no fuel leaks out. Does anyone know if anything like pipe tape or some type of waterproofing that is used around the threads where the line connnects to the carbureator?

MLA
12-11-2012, 11:21 AM
Metal fuel line connections on Carbs are typically a flare fitting, so the actual threads do not do any sealing. I would inspect both halves of the flares as well as the threads. If there is a nick or grove in the flare, or if its out of round, it will not seal. If the threads are not fully seating, they will get tight before the flare is tights. may need to replace those pieces.

milkmania
12-11-2012, 11:23 AM
spit ballin' here http://deephousepage.com/smilies/nixweiss.gif
http://www2.cougarpartscatalog.com/muc1014.html

OR

http://www.speedwaymotors.com/Fuel-Line-Tubing-Bender,2718.html

http://toolmonger.com/2009/03/02/harbor-freight-double-flaring-tool/

broncotw
12-11-2012, 11:30 AM
Are you using teflon tape???

thatsmrmastercraft
12-11-2012, 11:42 AM
While MLA is right in that a flared fitting shouldn't need any thread sealant, a wrap of teflon tape goes a long way to ensuring the fittings will thread together well and provide a leak-free connection. Inspecting the flare and fittings should be done every time a fuel line is removed.

kjohnson
12-11-2012, 11:42 AM
Are you using teflon tape???

It did not leak until I loosened it, so I don't think I damaged the line or flared end. Maybe I just need to take it to a boat mechanic.

I have not tried teflon tape. I tried that on a previous boat and it ended up partialling clogging the line.

TRBenj
12-11-2012, 12:01 PM
No tape on flared connections. Are you using the proper tools and tightening method?

thatsmrmastercraft
12-11-2012, 12:04 PM
When using teflon tape, you just want to use a enough tape to cover the male threads on the fitting and not have any excess to clog things up. Wrap it counter-clockwise with a very little overlap so threading the fittings together doesn't dislodge the tape. Be sure to use a 1" wrench to hold the carb fitting while you tighten the line fitting. If you don't use a wrench on the large carb fitting, you will not get the connection tight enough and end up with a leak.

TRBenj
12-11-2012, 01:36 PM
When using teflon tape, you just want to use a enough tape to cover the male threads on the fitting and not have any excess to clog things up. Wrap it counter-clockwise with a very little overlap so threading the fittings together doesn't dislodge the tape. Be sure to use a 1" wrench to hold the carb fitting while you tighten the line fitting. If you don't use a wrench on the large carb fitting, you will not get the connection tight enough and end up with a leak.
Why would you recommend using teflon tape for a flared fitting? The threads are not part of the seal.

thatsmrmastercraft
12-11-2012, 01:46 PM
Why would you recommend using teflon tape for a flared fitting? The threads are not part of the seal.

Post #5....

While MLA is right in that a flared fitting shouldn't need any thread sealant, a wrap of teflon tape goes a long way to ensuring the fittings will thread together well and provide a leak-free connection. Inspecting the flare and fittings should be done every time a fuel line is removed.

broncotw
12-11-2012, 01:59 PM
I have always used teflon tape for that connection and I have never had a problem with leakage.....

gweaver
12-11-2012, 03:51 PM
A comment on tape- the yellow stuff is double-thickness and considered to be fuel/propane safe. I would use that over the white stuff, which might degrade over time because of fuel exposure.
G

MLA
12-11-2012, 05:37 PM
Teflon tape acts as a thread lubricant. It can lead to overtightening, which can damage either or both halves of the flare or deforming the threads

mcparadise
12-11-2012, 07:04 PM
It did not leak until I loosened it, so I don't think I damaged the line or flared end. Maybe I just need to take it to a boat mechanic.

I have not tried teflon tape. I tried that on a previous boat and it ended up partialling clogging the line.

FWIW, the teflon tape for fuel is specific to that application according to my mechanic. i.e., it's a yellow vs white tape.....

Opsss missed gweaver's spot-on post..

ahhudgins
12-11-2012, 08:19 PM
Teflon tape acts as a thread lubricant. It can lead to overtightening, which can damage either or both halves of the flare or deforming the threads

I 100% agree with MLA. I have never used tape on a flare fitting and I never will. The flare is what seals the fluid, not the threads. If you try to use tape to stop a leak, you are not fixing the problem. Check both mating surfaces and make sure both sets of threads are clean. All is takes is a little bit of crud in the threads to keep the fittings from getting a good seal. :twocents:

Rossterman
12-12-2012, 12:15 AM
Flared fittings should seal on the flare, not the threads. Using tape to accomplish the seal comprimises the integrity of the seal and can lead to a leak developing later on with dire consequences. Lightly lubricating the threads is ok but if not sealing correctly, do a proper fix on the flare sealing areas and don't put your boat at risk!

mart_it
12-12-2012, 01:35 AM
+2 on not using teflon tape on flared fittings.

I think I know where your leakage comes from.

Your gas is most certainly leaking from the adapter fitting between the fuel line and the primary fuel bowl. You know the fitting which has the screen on one side? That's the one where the leak is coming from. If not seated properly on it's thin gasket, it may result in fuel seaping through.

Let us know what it was.

mikeg205
12-12-2012, 10:35 AM
Flare probably distorted if possibly over tightened. I would replace and make a new flared fitting get a new nut and have a fresh joint. Or get a flaring tool (cheap) and reshape the flare at minimum...IMHO.

I am really MCOCD and it doubles when fuel is involved...

kjohnson
12-12-2012, 10:55 AM
+2 on not using teflon tape on flared fittings.

I think I know where your leakage comes from.

Your gas is most certainly leaking from the adapter fitting between the fuel line and the primary fuel bowl. You know the fitting which has the screen on one side? That's the one where the leak is coming from. If not seated properly on it's thin gasket, it may result in fuel seaping through.

Let us know what it was.

I don't have a screen. Don't know if it was taken out by the previous owner or not. I tightened up the Adapter fitting prior to reading your email, started the boat and it did not seem to leak. I guess I won't really know for sure until spring, as it has been winterized as of last night.

kjohnson
12-12-2012, 10:56 AM
Thanks for all the comments and suggestions. Does everyone have a screen in their fuel line at the adapter connection? My 91 does not.

mart_it
12-12-2012, 01:57 PM
Yes, you will need a screen there. It originally came with one.
Good to know the gas isn't leaking anymore!

Kevin 89MC
12-12-2012, 04:53 PM
My '89 has a screen. Not entirely sure how critical it is, if that screen is stopping something that made it through the fuel filter, there are bigger problems than not having the screen there. I suppose if the filter disintegrates, it will stop that. But IIRC the screen wasn't super fine, and could let something through big enough to clog a jet anyways.
I also had a similar leak as the OP, thought it was the flared fitting, but it was the one on the bowl.
I also used to put teflon tape on flared threads, but agree with most here that if it is leaking, teflon shouldn't be used to stop it. Something is up with the flared fitting.
Kevin

thatsmrmastercraft
12-12-2012, 05:30 PM
The screen will filter out rocks and sticks, and is better than nothing. A good filter makes this screen unnecessary.

east tx skier
12-12-2012, 05:39 PM
1. It doesn't need thread tape.

2. The leak issue you have is very common. Basically, you have over tightened it. I don't remember what the torque specs are for that piece, but they approximate to "snugged up."

What happens is that when you over tighten the flared fitting, a/k/a the "little nut," it loosens the "big nut" on the carburetor fitting where it attaches. If you back off the little nut, you should be able to snug up the big nut. Then snug up the little nut, but don't over tighten it. This will likely fix your leak.

The big nut/little nut thing is my mechanic trying to explain this to me over the phone.

Here's a picture. I think this is what he meant.

thatsmrmastercraft
12-12-2012, 05:47 PM
I always say "Nothing tighter than a good cross-thread".:rolleyes::D:D

mart_it
12-13-2012, 08:28 AM
1. It doesn't need thread tape.

2. The leak issue you have is very common. Basically, you have over tightened it. I don't remember what the torque specs are for that piece, but they approximate to "snugged up."

What happens is that when you over tighten the flared fitting, a/k/a the "little nut," it loosens the "big nut" on the carburetor fitting where it attaches. If you back off the little nut, you should be able to snug up the big nut. Then snug up the little nut, but don't over tighten it. This will likely fix your leak.

The big nut/little nut thing is my mechanic trying to explain this to me over the phone.

Here's a picture. I think this is what he meant.

Just to clarify things....

That ''big nut'' is the adapter fitting and the small nut is the flared fitting for the fuel line.
If someone needs to remove the fuel line, you need to use 2 wrenches, one to keep the adapter in place, the other to untighten the fuel line fitting.

When putting it back together, you need to tighten the adapter first, use a wrench to keep it from over-tightening while you tighten the fuel line fitting back on.

I hope this helps!

east tx skier
12-13-2012, 11:56 AM
Just to clarify things....

That ''big nut'' is the adapter fitting and the small nut is the flared fitting for the fuel line.
If someone needs to remove the fuel line, you need to use 2 wrenches, one to keep the adapter in place, the other to untighten the fuel line fitting.

When putting it back together, you need to tighten the adapter first, use a wrench to keep it from over-tightening while you tighten the fuel line fitting back on.

I hope this helps!

Thanks. That is a much more clear explanation.

millpondkid
12-17-2012, 12:20 AM
I had the same problem this summer. Purchased a new flared line and problem was corrected. Also check the flare with flashlight to see if there is a hair line crack around it.