DA-50 problem

[Jole]

My brand new DA-50 engine on Somenzini Yak 54 with MTW canister mufler after one gallon of fuel runs very erratically and unevenly on full throthle.
I sow fuel in pulse line and big bubles in pick up line.Ther is no pin holes and the tank lines are OK and the tank is isolated by foam to eliminate bubles from vibration.
My engine was brand new, and at start it runs very good, until now.
I need advice to solve the problem.

Jole

[hawk21]

have you try adjusting the needles per the manual?

[reyn3545]

Are all of your fuel line connections tight? Be sure that everything (inside the tank too) is zip-tied... give the lines a good firm tug and see if they come off. Dubro makes some fuel line barbs, easy to solder on to the copper lines, that will do a great job of holding your fuel lines tightly.

If you see bubbles in the fuel line headed to the engine, there's got to be air getting in some how.

[Jole]

I did everything according to the engine manual.
I use DUBRO tank and bras lines so I'll have to inspect lines inside the tank.
Thank you for the advice.
What is about fuel in the pulse line?Is it normal?

[khan]

fuel in pulse line is ok. Bubbles in the feed line not ok. If all secure maybe some line has a small hole in it.

[hawk21]

missed the part that you see bubless in the fuel line,
have you verify the tank yet?

[Jole]

Yes I did, the lines in fuel tank are OK(outside and insida).Maybe ther is a pin hole or crack in carburator membrane so thats why I sow some amount fuel in the pulse line.I'll check it and let you know about membrane condition.

[JoeAirPort]

If I remember correctly, fuel in the pulse line on a DA 50 is not a big deal. I've seen that reported many times. The pressure pulse gets there regardless, fuel is not compressible.

[Jole]

If the fuel in the pulse line is OK than I'll pull out my engine from the YAk with gas tank and I''ll run my engine on test stand to see what is happening.

[JoeAirPort]

I've been seeing a lot of cases of carb bolts loosening on DA 50's. You need to just snug them up with Loctite. You don't want to compress the gasket. Also because of this carb loosening the gasket gets sucked in and creates an air leak. Check into that also.

[Jole]

I put new gas tank with new lines and the engine runs excelent.
Thanks everubady for helping me to solve the problem.

Best regards,
Jole

[Scott Gerber]

	Quote: Originally Posted by JoeAirPort
	I've been seeing a lot of cases of carb bolts loosening on DA 50's. You need to just snug them up with Loctite. You don't want to compress the gasket. Also because of this carb loosening the gasket gets sucked in and creates an air leak. Check into that also.

Just the exact thing that happened to me this past weekend. However, I did have the carb off early this past spring to replace the blue gasket between the crankcase and reed block because it was beginning to suck in. I also had to flip the carb to correct a running problem but that's a different matter. When I put things back together I used a thin slime of red copper rtv on the blue gasket to help "glue" it into place pulse I used blue loctite on the carb bolts. When I tightened the two bolts I took them down until they just seated then 1/4 turn more. The engine ran great all summer long until last Sunday where during an extended full throttle flight (playing pylon racer with a fellow flyer) I heard the engine start to bog down. I throttled down and landed where the engine died at idle. While the engine was hot there was little to no compression when pulling the prop through. That night I pilled the engine and muffler where I found about a 1/16 inch gap between the carb and reed block. Also, there was some light scoring to the piston skirt and ring. It's all going to DA for fixing up over the winter...


Scott