The Tanks Only 50 years old , do you need to put fuel in it , or is some still there . 

Blankety feed pipe mayve snapped inside , try tilting the plane about with a long length of tube fitted to the feed , and try sucking and blowing , to see .

The black foam meat tray type thingos at the supermarket make good packers / spacers for shimming tanks .

Some Dudes like SILICONE , like the fish tank / window / no more leaks clear tytripe for glueing in tanks .

Armourall Here now isnt good . Some People are saying it screws your glowplugs , anyway .
But if it loks like those wirde noodle in your filter , it may be armourall siliconeing it up .

If You Stand your plane on the outer tip , youd think it'd feed neat fuel , not bubbles .

     Hello Matt:

     No, the tank did not have any fuel in it.  I could have sold the fuel on E Bay to be period correct for a person who flies Old Time Stunt!

      I turned the plane with the outboard wing down and sucked the fuel out of the tank to determine if this caused any bubbles in the fuel line. Nada! I turned the plane with the outboard wing down while the engine was running and I still got no bubbles! How can bubbles form when the pickup tube is submerged in nearly 2 inches of fuel?  The next thing is to strap a tank designed for a profile plane to the outside of the plane to determine if indeed it is a vibration problem or a bad built in fuel tank.  I checked the built in tank for leaks and again, Nada.

     Perhaps I should just hold a tank in my hand while the plane is running to isolate all vibration.  This will require some thinking out of the box! Lol  No problem.  Just remove the external tank from the plane after the plane is running and hold it in my hand away from the plane.  I think that this is a job for at least two people! Lol It should  provide couple of exciting moments.   This is where one finds out who his real friends are! Who says modeling is not exciting?  Just cut the rubber bands that are used to hold the tank to the outside of the plane while your helper, former friend, holds the plane. Hold the tank away from the plane and see if the problem goes away.

     There must be a more simple way!!!!!! Lol " I picked a bad time to stop drinking."



                                                                                                             Be well my friend,

                                                                                                             Frank

     

Are you using an in line fuel filter?

Well, that was my one tip, but looks like it's no good for your situation.
At least I will find out what worked when you do....
Hope it's soon.

what of the exalted Armor All soulution??

   Hi David:

    I tried it with no success.

                                                                                Frank

     Hi All:

     Thanks for the replies!

     Ty: It is not a Fox!  It is the old TL OS .35S that he converted to a .40.

      I checked tank with air pressure while it is in the plane but a leak in a fuel tube that is in the plane may not show a leak doing this.

      I will cut the tank out of the plane (ugh), and check for leaks while the tank is submerged in water.   But before I do that, I will strap a tank made for a profile on the outside od the fuselage to see if it too produces any bubbles. If so, vibration may be a problem.

     The tank has most likely been in the plane since it was built circa 62-63.  There may have been some corrosion that has developed in the tank since then. This also prods me into removing the tank.  Is there an easy way to remove a tank that has been glued in place for decades? Lol

                                                                                                          Be well,

                                                                                                          Frank McCune

If it's not the tank, maybe a leak in the fuel filter or fuel feed line? Or maybe the tank is loose in the airplane?  Have you gotten it out yet? I would cut out the bulkhead behind the engine and make the tank removable that way. Yes, it's inconvenient to have to take the engine out to adjust the tank height...but less inconvenient than cutting it out yet again.    Steve