I have a new engine that only has a few tanks of fuel through it. I've had lots of help from some of the more experienced members of my club in getting it tuned and it seems to run fine while it's running. My problem is that I only get a 6-8 minute flight and then it deadsticks! I pulled the tank out to see if I had a clunk problem and I found that I still had 2/3 tank of fuel left! There is no problem with the clunk.

Engine: GMS .47
Tank: 9 oz (270 cc)
Plane: Avistar 40
Fuel: 15%

Any ideas???

Too Lean on low end is my guess. I had that problem....richened the low end and re-tuned.

Count the turns or seconds it takes to fill your tank. Take out 1/2 of the fuel and tune your engine slightly rich from max RPM. This will ensure you are not going lean due to low fuel. Did you check for leaks in your clunk line when you had the tank out?

Did you try running that thing on the ground for 6 minutes?

I know I will get blasted but I had a very similar problem with 2 different engines.
A TT Pro 46 and an OS 46 ax.
Bottom line, I was told by club members that 2 cycle engines do not like 15% fuel. Yes if you are lucky and dink around with the motor you may get it to work.
Say what you want but after I switched back to 10% my problems were over and both engines run like a top now.
I am not saying it will solve your problem but if you can borrow a tank of 10% fuel from a flying buddy you can test it out.

You and I will both get blasted because I did the same thing too.

Change the INSIDE the tank fuel line. It may be perforated, then after 6-8 minutes the fuel level the perforation gets exposed, sucks air and the engine dies.

I've been running 15% Cool Power in all of my engines for 10 years now. Never had a lick of problems. That includes everything from a 20 size all they way up to a 120 size 2-stroke. They run just fine.

Ken

No blasting but the club members are simply without knowledge.

Bill

Did you check to see if you installed the tank upside down? (Not that I've ever done that....[])

R,

SLFlt

New engines will suddenly stop in flight until you get the lowspeed needle set well. They'll very often run and sound good but suddenly stop in the air.

Take a few minutes and do the pinch tests to check that lowspeed needle. I betcha it's not spot on. The pinch testing doesn't take any time to do.

To add some info, this is the second engine in this plane. I first had an OS 40 LA for almost a year, but I grew tired of the Yugo-like top end.

I will replace the fuel lines and brass tubing, and flush the tank with some leftover fuel. I will then try the low speed needle adjustments and pinch tests. If that fails, I will try out the 10%. If I still have the same results, I'll come back and post a reply. Thanks to everyone for their advice.

- Ryan

Chalk up another person who uses 15% Wildcat in my .46's (LA and AX) for years without any problems. And they are powerful too!

running with the 1/2 tank is a good idea. i haven't even tried that! :-)

the reason you'd want to do that is the ensure that you're getting enough gas even at low gas levels. you might want to check the level of the carb. if your engine is mounted up right, your carb is likely above the middle of the fuel tank. that means when the fuel drops below the carb, it'll have to work to suck that fuel up, hence the leaning out and dying.

the good thing is that deadsticking is a part of flying so at least you're getting a lot of practice!!!

Sorry, all I use is 15% also. I'm voting on a hole in the clunk line or just running too lean possibly even due to tank position.

I agree! All I use is 15% and it works just fine. If you installed the fuel line that came with the tank, that could possibly have holes in it. The stock fuel tank lines are usually thinner and can get holes in them very quickly. Or it just could be that the carb isn't tuned in yet and you need to set your low speed needle again. Do you have an inline filter between the tank and the carb? Sometimes they can leak and lean out the engine.

I did, but some of the members of my club told me to get rid of it, as I was filtering the fuel between the can and the plane already. I'll add checking the tank height to the list, as I had recently changed engine AND mount.....

Thanks,

Ryan

I had an OS40LA with the same problem.
Switched from 10% to 15% and problem went away.
I fly at around 2,000 feet elevation.

I'm only going to blast those who make such a flat statement.
There are to many variables.

KW_Counter

Deadsticks Cured!

The fix ended up being the tank hardware. I pulled the tank out and the brass tubing looked horrible. The tank walls had some gumming as well. I replaced the brass tubing, clunk, fuel tubing, and cleaned the tank out with alcohol and a toothbrush. Now I'm getting 9-10 minute flights when I'm flying at half throttle and 8 minutes EXACTLY when flying around full throttle. Thanks for all the help.

- Ryan

Had to be external to the engines if two engines were having the same problem.

Don't Forget To Check The Preshure Side Of The Tank.If The Tank Is Not Getting PSI It Will Do The Same Thing.A Strange 1 That Happened To Me ,The Muffler Was Loose The Nut Came Loose On The End. So Make Shur Every Thing Is Tight.
15% Nitro And 18% Oil Is The Only Thing To Fly With.[8D] [>:] [X(]

I had the same problem on my GMS .47. it flew great but deadsticked after 6-8 mins. I changed to a castor oil fuel ( I had been using Coolpower and I switched to Omega 15%) and I took high-temp silicon ( comes in a tube) and removed the back plate and put a bead of silicon around the rim of the hole where the back plate goes.Then re-insert the backplate and do the same thing to the carb. this fixed the problem for me completely. The GMS engines need the castor oil so at least use Omega or similar fuel. And some need the silicon sealing. It cant hurt and the silicon only costs a few dollars but make sure to get high temp. I found mine at an Advanced Auto Parts store, a NAPA store would have it to.
Karter

I had a 40 LA about 10 years ago, I switched to a better engine and the problems went away!

15% is fine. Been running it for years.

Like others have said, check the fuel tubbing inside the tank.....OK, just saw you fixed it. OK, also check the metal tubing

Anyway, the first thing I do with an engine problem is check for:

Ignition check
1. Different glow starter
2. Different glow plug

Fuel check
1. Carb adjustments
2. Fuel line plumbing

Never had that list fail to find the problem

about the filter here are a few things that you are not considering about the fuel. First you said that the tank was gummed up a little, well new fuel loosens up that gunk and it floats free inside the tank waiting to be sucked up by the clunk, two you are introducing pressurized burned gasses and junk from the exhaust to help pressurize the fuel system. Does this sound like the fuel is really that clean even though it was filtered from the can. Personally I like to use fourmost fuel filter on my planes because they are very small and light and provide backup to my filtered can fuel.