In Reply to: Re: Stopping fuel leaks at fittings posted by Rustyal on October 17, 2018 at 11:53:00:
The fuel valve assembly goes into the tank with a tapered fuel thread that should not need anything to seal. Same for the threads where the fuel elbow screws in the carb. However, old tapered threads may be deformed or scored, so I use a sealant. Not the white teflon stuff. That is for water lines. For fuel lines get the (usually yellow) tape or liquid thread sealant for gas/fuel lines. The hardware stores should have the different types of sealants together, or they may have the fuel line sealant near the gas water heater or gas fireplace installation kits.
When applying sealant to tapered threads, leave the first male thread that will go into the carb or tank completely clean. Cover the rest of the threads with sealant. Start the fitting by hand then start snugging with a wrench until the fitting is pointing the right way. It is hard to describe how tight a tapered thread needs to be, but if you turn past where the fitting needs to be you cannot back up or it will certainly leak. If turned past the correct location, they have to be tightened until they come around again.
To repeat what Bruce said, do not apply any sealant to the straight threads on captive nuts that secure flare tubing into flare fittings.