I have a Super Stick 60 with a O.S. Max .65 LA engine. When I take all is good until about 3 min into the flight. After about 2 min it starts to spudder like it wants to kill. I land and check it out and I notice that I have a lot of bubble coming from the line that comes from the tank to the neddle valve. I've change the lines and still get the same results. I am at the point where I want to just change the engine out. Any help will be appericated.

You may have a fuel tank position problem. If you can ,you want the center line of the tank inline with the centerline of the carb.

Did you replace the lines inside the tank as well? Also check the brass tubes the pass through the stopper for cracks. (that one drove me nuts for quite a while.)

Definitely inside the tank. I have seen pin hole in the inside tubing do just this.

Don't think this is an engine problem.

Tom

It amazing how much knowledge is on RC Universe. All of the above I did not check. Will be up late tonight checking them all.

When bubbles are seen it is usually a line leak and it can be inside or outside the tank. It can also be a loose bung or crack in the tank. You can pressure test the tank before you open it up or after you replace lines by plugging the lines except for one, hold the tank under water and blow very hard on the open line and look for bubbles, that will show you if the bung and outside lines are OK or if there is a crack in the tank. If no bubbles then it's pretty sure it's an inside line problem.

Or if you have one of these or know someone that does, you can use that.

I'm not aware of any engine malfunctions that can cause bubbles in a supply line. Bubbles in that line mean there is an air leak somewhere before where the bubbles appear, not after.

My guess is Crossman nailed it. Fuel in the full tank covers the leak then when the fuel goes down air can get in. Be meticulous in smothing all the tubing and replace all the lines.
I would give a CLOSE eye to the rubber stopper as well.

Fuel will pick up vibration from the engine and foam up causing a lean run. This gets worse as the fuel gets lower. No wood to tank contact and place foam all around the tank.

Good luck

My guess would be the inside main line too but pressure testing after you assemble a tank is something you should always do. They now put in an anti foaming agent in the fuel and it works quite well. I have several planes with tanks hard mounted. Foaming is pretty much a thing of the past.
SCOOTER???????? You been over to the strip drinking those $1.00 Margaritas at Casino Royal????[8D]

It could be a vibration issue as well. As the fuel goes down in the tank, there is more room for bubbles.
You can buy on of these bubbleless clunk and make sure your fuel tank isn't in direct contact with the airplane fuselage in order to minimize vibration (use foam to isolate the tank). I've already got this trouble with my nexstart. And of course you can first check all the fuel lines and tank for leak.

what is that used for in regards to fuel taks

My girlfriend is a bartender, I drink New Castles for FREE....[8D]

It is a pressure/vac pump with gauge. You can check the the whole fuel system from the carb line to the muffler in 10 sec in the plane. If you find that the system is not holding, it is easy to identify the problem by either bubbles or leaking in the system.

My guess would be that the tank is vibrating and causeing the bubbles. Have you wrapped the tank in foam
to keep it from bouncing around. Give that a try also.

Maybe just lucky but I have never had any trouble with bubbles etc. and never have tank in foam. Always securely mounted in tank area.Whatever worksd for you.

how much does it cost?

OS makes a "bubbleless clunk" that works pretty good. It should.. they want $15.99 for the darned thing. (the first one, the one on the left)

http://www3.towerhobbies.com/cgi-bin...&I=LXXF25&P=ML


Dubro also makes a fuel filter that works just like the OS one for a heck of a lot less.. Tower has it for $2.49 (the second one, the one on the right)

http://www3.towerhobbies.com/cgi-bin...&I=LXD741&P=SM


I bought several of the Dubro ones and use them on all my planes. I never had bubble problems, so I can't say if they work or not, but, as I said, I don't have any fuel line bubbles at all.

CGr.

mrcoolpop,

take apart the fuel tank and test all the tubing. The best way to do this is put a fuel dot (or a screw) on one side of the line, hold the whole line in a bucket of water and blow as hard as you can on the other end. If there is any leak you should see bubbles. They do the same with the other end (the one through which you blew first) clogged.

Once all the lines are tested and you are sure there are no leaks, assemble the tank. You may use a standard or bubble-less clunk and then pressure test the tank the same way.

When installing the tank in the airplane, use as much foam padding as possible to isolate the tank from vibrations.

See whether you can lower or raise the tank to the centreline of the carb. It is not very critical that you match the centreline exactly but it needs to be close if you model allows it. Ensure that you connect the tank correctly i.e. carb line to carb and vent line to muffler. See whether your engine has the same problems after this

If all else fails, use a Sullvian flexitank on the link below.

http://www3.towerhobbies.com/cgi-bin...?&I=LXFU64&P=7

If you are having foming problems, this tank will likely resolve them as it is a soft tank and will absorb vibrations. You can also try the bubble-less clumk sugested by CGR.

I just had problems with a 55ax not running properly just like yours though I didnt note any bubbles. After I put in the flexitank and clunk and a club expert tightened my head bolts, the engine runs fine. Dont know which of those was the problem, but if it runs dont test it.

Best of luck resolving the problem

Ameyam

The often quoted ( and incorrect ) response for RUNNING engine problems....

The "centerline" problem really only applies to siphoning when the engine is on the ground and not running. Centerline adjustments are merely used to prevent hydro lock.

With any standard small ARF the centerline is displaced by up to 4-6 INCHES every time the plane goes nose up or nose down.

If the engine was SOOO sensitive to the .5 to 1" centerline offsets that could POSSIBLY exist in an ARF ( usually because of mounting the engine differently than what the plane was designed for ), we would never be able to fly our glow planes up or down.... only level.

His engine ran just fine for the first three minutes, which as others have already noted points to a plumbing problem, hole, or foaming issue.

If you doubt this, see the "Fuel sticking to the back of the tank on downlines" discussions and associated video for empirical evidence.

Make sure that you do not have some dirt or debris in the actual nettle valve. This has caused me problems in the past. The engine runs great for awhile then quits after a couple of minutes into the flight.

Disconnect the fuel line on the valve from the tank. Then take the nettle valve out. Get a long piece of fuel tubing and put it on the outlet running to the engine.

Place your finger over the fuel intake on the nettle valve assembly and suck on the fuel line attached to the outlet going to the engine. If there is any debris in the valve this will usually free it. Be careful not to choke yourself.

Once you have done this replace the nettle valve. Take a piece of fuel line and attach it to the inlet on the valve that comes from the tank. With the valve open you should be able to easily blow air through the valve.

Once you get your problem resolved put a filter in the line coming from the tank.

Hope this helps.

That tool above is a Mityvac, google it. Used itmany times when I was in the auto trade. Would indeed be very handy for checking model fuel systems. Can suck and blow normally.

does the 65 LA have the remote high end needlevale just like the 61 FX ? its possiable if your seeing the bubbles come from the vavle to the Carb " clear small line maybe 2 inch " that the vavle houseing is sucking air , and the air isn't come from the fuel tank pick up line .

one thing do you have a known good fule tank that you can use for testing on a stand statickly ? it might narrow it down

just a Idea

if that doesnt work there is always electric

If you think its anything with the tank Id just replace it. There only $5 or $6 bucks.

Jimmy

IMO, it's a vibration issue which does not show at first, due to a full tank. After some time, the fuel level lowers to a point at which the still present vibration causes excess leaning of the mixture, which leads to power loss/engine quit.

For starters, try a different prop, and if you are running a spinner, make sure it is in good shape and spinning true.

Good Luck!

PS: I have seen a tank foam up, like a Maytag clothes washer, due to bad engine bearings!