N410DC

I am just getting back into the hobby, and purchased a gallon of 10% nitro (plastic bottle and cap). I bought some fuel cap fittings. Once installed, will the cap fittings, lines, and pump create an airtight loop (and thus inhibit moisture buildup), or should I remove the cap with the fittings and seal the bottle when I am finished flying for the day? If the bottle should be sealed, what is the best way to do this, if I have poked holes in my only cap?

1QwkSport2.5r

While I don't bother changing caps on my pump jug because I keep it in my house, you can recap the jug. Windshield washer fluid jugs have the same types of caps. As long as your cap fittings and pump are sealed well/tight, it's not necessary IMO. Just my take on the subject though.

Hemikiller

My Feedback: (125)

Just leave the cap with the fittings in place and you'll be fine.

wcmorrison

My Feedback: (2)

I have been using a fuel cap with the typical fittings for refueling for years with no problems. No, I do not recap. Sometimes I go as much as a month without flying due to weather (well really winds). I never have had a problem.

SrTelemaster150

I have had the same cap on my fuel jug since the late '90s. Plug your fill line onto the vent & the fuel will stay good. I hauled a partial gallon of 15% Cool Power W/the cap & fuel lines set up like that out of a closet that had set for 14 years right next to an unopened jug. i strained it through a coffee filter to filter out some fine white particles & tried it on my test stand. It ran just as good a the unopened jug which performed the same as some brand new 15% Cool Power I bought @ the LHS.

Ernie Misner

What brand is your fuel cap fittings? The DuBro and Sullivan/Slimline types have a small o-ring on the probe that seals very well when you put it back into place in the cap. No need to remove or put the stock cap back on the jug at all.

SrTelemaster150

The OP linked the Dubro cap on Tower's site.

No need for an "O" ring, Just push the fill line over the brass vent tube stub.

Ernie Misner

Both DuBro and Slimline come with a nice little o-ring on the probe. We're talking the fittings on the jug cap here.

SrTelemaster150

I have the Slimline Excel probe & I just use a short piece of fuel line on the vent stub. The fuel line will stretch enough to go over the slimline probe.

Ernie Misner

I guess I'm confused.... The OP was asking about how well the fuel jug cap fitting did seal. Isn't this Slimline Excel Probe designed to go in the airplane for a convenient way of filling the tank?

SrTelemaster150

The OP wanted to know if the fuel lines could form a "loop" that was sealed. He secified the Dubro cap.

The Dubro cap vent itself doesn't have anything more than a metal tube stub (on the left) that requires a short piece of fuel line to plug the "probe" into. On the right is the fill fitting that has provisions for a tube on both ends, one to go to the clunk/filter in the jug, the other to the fuel fill probe. I'm not aware of any fuel probe that will seal when plugged into the metal the vent tube itself.




However, just about any "probe" whether it has an "O" ring or not will seal when plugged into a piece of fuel line tubing. Loop the fill line/probe to the vent line & you have a sealed "loop" just as the Op asked about. The Slimline Excel probe, even though it is much larger than the typical fuel probe used W/standard fuel line filling will still seal when the vent tubing stretches over the end.



My set-up is actually the Dubro fittings used W/the inner portion of a standard fuel jug cap.