DaddySam

My Feedback: (9)

Just a quick question to make sure I'm on the right track:
I have a DLE 30 in a 25% Yak that I've been flying for years. Last week I replumbed the tank with new line as I do every year. Went to fly yesterday (first of the season) and the engine started and ran fine but dies at wide open throttle. In the air and on the ground. I replaced the plug (NGK CM6) and same thing. Ignition battery is fine. There did seem to be more resistance when I filled the tank so I'm thinking the felt clunk might need to be replaced. Any thoughts? I did open the high end needle a bit and it just sounded rich. Again, this engine / plane combo has been flying for years without issues. The fuel is from last season (Stihl Ultra at 50-1).
Thanks
Sam

ahicks

My Feedback: (2)

You were too lean. Cooler air is much denser, and contains more oxygen. To maintain that optimum mixture of fuel and air it takes to make good power, you need to add more gas. When you get it set right in these temps, you'll need to set it again when it gets warmer - because then, the situation will be reversed. Lighter air w/less oxygen will need less fuel.

The reward for adding the fuel to denser air will be more power. Often noticeably more power!

jerdavis

My Feedback: (3)

Sounds like the fuel pump is not working. Try replacing the pump diaphragm in the carb and/or check the pulse port for being blocked. A leaking pulse port cause the pump to not work, so check for an air leak around the reed block and carb. Also , an obstruction (dirt) in the high speed needle will cause that.

Hope that helps

Jerry

pe reivers

More resistance while filling the tank??? Through the felt clunk? What is that felt clunk good for if you fill through it. It deposits all debris on the carb side, and in flight it is transported to the carb. Use a dedicated line for fueling only to bypass this problem.
My best guess is that you need to clean the internal carb filter. Hold the mesh filter against light to make sure it is clean like new. Often gum clogs the narrow passages.

capnduane

It doesn't take much of anything to impede the flow thru the little round carb filter. A small bit of lint will do it. I run inline filters on all my engines for this reason.

av8tor1977

My Feedback: (6)

Yep, for this very reason is why I have gone to three line tanks on my planes. I have a filter in my fueling tank/rig, but still, I like the 3 line system because you are not pumping fuel in ahead of the fuel tank filter, and the flow system from the in-tank filter to the carb remains complete and undisturbed while fueling or de-fueling. Less chance of an air leak in the critical line to the carb, less chance of CREATING a leak in the line while fueling, no introduction of air into the main fuel line while fueling, less chance of dirt getting to the carb, etc., etc., etc.

It only takes a very tiny air leak in the fuel line from the tank to the carb to cause a fuel pumping problem for the carb, and obviously, only a little dirt in the fuel system can wreak havoc as well...

For the original OP; check your carb inlet screen as has been mentioned, change your in tank fuel clunk/filter, and use fresh gas. Year old gas/oil mix? Not in my planes...

AV8TOR

DaddySam

My Feedback: (9)

Thanks to all for the good advice. I have to admit my only reason for using a two line system is that I'm lazy. But since I am down to two gas planes right now I am going to convert them to three line. I do have a filter on the fuel can but the observation that if there is any dirt in the line i would be putting it ahead I'd the clunk makes sense. I'll add the fill line and clean the screen and report back the results. As for old gas I understand the oil contains a stabilizer agent. In a ideal world I would use fresh fuel but I did not fly much last year. Thanks to all again.

av8tor1977

My Feedback: (6)

I would still put the fuel into a car, lawnmower, weedeater, whatever, and run fresh fuel in my plane. They say the oil has stabilizers, but my experience is that the fuel begins to degrade from the moment it is mixed with the oil, in addition to the normal degradation of fuel over time. Doesn't cost that much to have fresh fuel in your "pride and joy".

You might be able to clean that clunk felt by soaking it in acetone, but a much better option would be to replace it with a new one. As PE mentioned, you almost have to remove the carb screen to really inspect it. The handle of an exacto knife works well to re-install it.

AV8TOR

DaddySam

My Feedback: (9)

Well here is some of my progress. It shows you're (I'm) never too old to learn something new. Pic one shows the carb screen in the carb, pic 2 shows it out. I cleaned it and now it looks brand new. The tip on the Xacto knife was right on. Thanks a million. I'll post after my test run this afternoon.
Sam

av8tor1977

My Feedback: (6)

While you are at that point, go ahead and take the regulator cover off the other side of the carb. Check to see that the rubber diaphragm is nice and supple. If it is at all stiff, replace it. If you should happen to get things mixed up, the gasket goes on first, then the diaphragm and then the cover.

AV8TOR

DaddySam

My Feedback: (9)

Thanks. I did, because I wasn't sure what side the screen was on and I guessed wrong first time. The rubber diaphram was wet with fuel and seemed supple. I think I should probably get a spare for next year though. Do you know of a source? Also, just ran the plane in the side yard, and after re-adjusting the needles, it runs great.
Thanks again for all the great, spot-on, advice.
Sam

av8tor1977

My Feedback: (6)

Hi. Glad you got her going again and way to go!

There's lots of online sources for carb parts. Do a search and you come up with bunches. I sometimes buy parts from Small Engine Parts Warehouse, and Jack's Small Engines, but I buy carb parts where ever they are cheapest the day I am looking for them. Dave's Discount Motors, (www.davesmotors.com) also has some deals sometimes, but look around for those carb parts. I buy those diaphragms by the 10 pack, but I'm sorry I don't have the link for where I bought them the last time.

Have fun flying,
AV8TOR