I bought a used 46FX and put it a new tower uproar...It runs great on the ground, point the nose in the air and it still sounds great, idles fine...it's actually a little on the rich side(high end needle)...fly for about 1-2 minutes and the engine will lean out a little(where it actually sounds right where it should be) fly for another 1 minute or so, then motor will quit, it won't lean out and quit like when you are running out of fuel, but rather it just suddenly quits...I have replaced the fuel lines and replaced the tank, new glow plug. There are no air bubbles at all in the lines, checked to make sure all the engine bolts were tight. Everytime though this happens, I land plane dead stick, there will be noticable exhaust oil on the wing, but the engine will be extremely hot. I have never had this problem before with numerous planes and engines...could this be something with the engine, since I bought it used I really
don't know it's history...

p.s. I am running omega 10% which I run on all my other engines with no problem...and I am using an 11x4 prop, I know it's a low pitch prop...could that cause it to run to fast and heat up? I don't have a tach so I can't check it..

thanks
-Bill

Have you rechecked the lines inside the tank? Could there be a pinhole in the fuel line that sucks air when the tank gets low enough? Did the clunk get forced to the front of the tank?
Are you sure the fuel lines arent reversed like the carb is getting fuel from the vent line untill the fuel gets too low? I had an FP40 do this, never did figure it out, changed motors.

I think the FX 46 runs better with an APC 11x5 or 6 but as long as your rich enough the 11x4 shouldnt be a problem.

I actually replaced the line inside tank, I did check the to make sure the lines weren't reversed(I read that on here somehwhere)...the only other thing I can think of is maybe somehow during flight the fuel line is getting pinched...it is a little long and has a bend in it, but if I make it shorter I won't be able to reach it to fuel it since it has a remote needle valve. But if the line is getting pinched I would think it would happen right away, not after a couple of minutes...

thanks!
-Bill

Check the brass tubing in the tank, too. Since you bought it used, as you admit, you don't know the history. It may have been crashed, causing this problem.


Dr.1

Yeah I have, as I have actually replaced the tank...however this morning I found two things which may be causing my problems...

1: The nipple on the muffler for the pressure line looks like it was put in slightly crooked, so I put some RTV sealer around it, thinking maybe I wasn't getting the back pressue I should.

2: After removing the tank for the 1000th time I noticed I could easily pull the brass tubing out front the tank even though the screw is tightened down...so I figured maybe from opening up the tank a million times it lost it's ability to seal everything tight...so I happened to have an extra dubro tank and used the parts from it and it is now sealed up real tight...

So I am going to try today to fly it again and see if that helps!

-Bill