Hi Guys, I did do multiple searches, but here is the question anyway: I am having trouble with the engine cutting at 1/2 to full throttle (I'm pretty sure it is just a lean/rich issue, which I will resolve tomorrow) BUT my question is:

Is there ANY reason to see bubbles in the line other than something being wrong (e.g. tank leak, tube leak, etc).

The bubbles are not present when the engine is running, they are only visible before/after starting engine. I DID SHAKE THE FUEL TANK AROUND A LOT WHEN I WAS FIRST FILLING THE TANK, so I could see how full it was. Maybe this caused the bubbles.

If this helps, the fuel runs backwards from the carb to the tank after priming, before starting the engine. Is this normal/pressure loss/something to do with the bubbles?

ps I have a new Hobbico Superstar with OS max-40 LA.

THANKS

test

Yes, having the fuel run back from the carb is sometimes normal. If there are bubbles in the line after the engine has been running a few seconds, then there is a problem. if there's one bubble that stays put, then don't worry about it. If you can see bubbles moving up the line, then the fuel is foaming or there is a leak.

Make sure the tank is surrounded by foam rubber that is not compressed too tightly. Also make sure the propeller is balanced (spinner too).

What if there are no bubbles while the engine is running (i.e. there is a steady stream of fuel while the motor is running?)

Then there is no problem.

Hi paul_c,if there is no bubbles present while the engine is running then all is normal,now go fly.

THANK YOU ALL, THE ENGINE IS BROKEN IN AND RUNNING STRONG AND SMOOTH (after 3 tankfulls) ;-)

I have the same plane/Trainer and never saw any bubbles.
No bubbles while running is fine but on mine the fuel does not run back.
Maybe a tiny air leak???
Also on another thread I saw where the adding a fuel filter helps with any foaming of the fuel.
Sure it wasn't foam?
Because foam and bubbles would go to the top of the tank and your drawing from the bottom.
Next time don't shake the plane.
Before you start it choke the carb with your finger and turn the prop by hand.
It should suck fuel up the feed line with no bubbles.
If you see any then perhaps you may have a tiny air leak where the line draws from the tank.
Just giving my 2 cents on what I just did here.
PS: What brand fuel??

It is Omega 10%. And it could have been foam rather than bubbles. The engine seems to be running fine, so I'm not going to worry about it at present. I'll show my instructor next week, if this snow here in NJ ever finally melts away!

The fuel will run back if the carb is open and the tank is slightly lower than the carb. It's not a big deal. It happens on most of my planes. I just choke until I see fuel actually enter the carb and then stop.

Once the engine is started, it will run long enough on the choke to start drawing fuel.

In other words, it's not something to be concerned about.

Good tips Whirley Bird !

Yes, I do see how the fuel does get "pulled" back into the carb once the engine turns over.

Thanks!

Hi LadyFlyer.
OK First ,
Thanks for the thumbs up.
Second I've been around and made a failed trip to the North Pole.
640 miles short.
You say your North of Canada.
I climbed the Mackenzie mountains to the Beaufort Sea but thats N/W .
Are you on one of the islands?
Maybe N/E and live in Greenland?

is that lady flyers pic on her avatar? if so, shes kinda hot. =X

I know NOTHING of her.Send her a PM and ask

Hi Lady Flyer. Ummm... my name is dainjarouz. You don't know me, but... umm... are you kinda hot?


I'm sure that will go over real well. lol

more like...so ive heard you like rc planes? *incoming low flying trainer zooms by* ....so do i ::wink wink::