I am having problems tuning the [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=EVOE100]Evolution Trainer Power System [/link] engine in my Alpha 40 trainer. The trainer was crashed and I rebuilt it. There was enough of an impact to break the High Speed Needle Valve (HSNV) off of the engine. I replaced the tank, fuel lines, high speed needle valve, glow plug, and prop. I wanted to get her in the air to see how the rebuild went, and she flew fine at WOT for several minutes. Throttling down to land ended up with a dead stick landing because of an engine out.

I replaced the glow plug again (first replacment was a used one, this one is new) and have new fuel in her, but she does not stay running. She starts just fine but throttling up quickly causes it to die unless I go to idle. (Sometimes it stays running, but sometimes it does not.)

I can sometimes SLOWLY advance to full and I can adjust the HSNV but it may run like that for a bit then die. She idles fine. I tried pinching the fuel tube while at WOT and she drops RPM and dies so I richened her out and this was fine for awhile.

The HSNV is brand new so maybe the limits are set wrong? I wanted to ask before I did anything.

I am at the point where I am ready to send the engine in for diagnostics but did not know where or how much that would cost. A new one is about $80 so would it even be worth repairing by the time I pay round trip shipping, diagnostics, parts/labor, etc? I know you cannot answer that because you do not know what the problem would be but I am thinking on the low end it would be about $25.

Thanks.