My buddy HT sold his Edge with a ZDZ-40 to another flyer. The engine used to run fine in the plane. Now it behaves very strangely. The engine can be adjusted so it runs well on the ground. After a few minutes into the flight it starts sputtering and sounds extremely rich - very low power. If you keep flying it will eventually die. It behaves like someone closed the choke. We checked the ignition battery, and it showed good voltage under load (2700 NiMH 4-cell pack). I can't imagine that it's air pressure in the cowl because the engine used to run fine and there weren't any changes made to the cowl. Perhaps it's a flaky ignition switch? Anyone have any other ideas?

Perhaps it's a flaky ignition module...They do become intermittant sometimes.....

Also, I've seen similar symptoms when the ground lead is loose from the engine.....

Or, it may not be ignition at all!

I've had this kind of problem myself when I used a supposed gasoline stopper in a fuel tank (I think it was Sullivan that had marketed a lot of stoppers with the wrong color a couple of years ago, and later found out it was for glow!).

It started to disentigrate, and contaminated the fuel. I went through several flights with the symptoms you describe until she finally died (sucked all the goop into the carb)......

Just a thought.....

Those are all good ideas. The tank is a Bennet Built with his fittings so that eliminates the stopper disintegration. I don't know if he has a clunk filter in it or an inline fuel filter or no filter. The ignition ground is via the metal shielding on the HT lead and cap, but that could be a problem if it is not making good contact with the metal "well" under the plug.

I think we'll try to run a full tank out on the ground, and also try a flight while bypassing the ignition switch.

Maybe the guy is using 7-11 gas & Klotz oil?

Sounds like it may be overheating, did he try to fly it with only 1/2 o4 3/4 power. Ken....The "BALSA BANDIT"

I think we did try a tank of a known good fuel, but my memory is a little foggy now. It doesn't sound like an overheated motor, it sounds like a very rich motor (blubbery rich like the choke flipped halfway on).