Fr8dog Posted July 22, 2021 Report Share Posted July 22, 2021 My RV12 with the 912ULS will not run smooth at WOT or get T/O power after it's HOT. Last flight everything was fine until I left the power up at altitude to see what I could get for RPM in level flight. It stated to run rough at 5400 RPM. After returning to the field I as unable to get more than 4400 RPM. The problem is always after the engine is hot. Don't waste your time with suggestions to trouble shoot only because we've been through everything at least twice. But please, if you have had or know someone who has had the problem of not running at full power after the engine gets HOT, I'd love to hear what fixed it. Ron PS; I realize I'm just a lurker on your forum but I'm about to make Coors cans out of this airplane and could us someone's help to prevent that. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted July 22, 2021 Report Share Posted July 22, 2021 Hi Ron, I have numerous questions to ask before trying to pinpoint the issue. You're welcome to call me at the number below. I'm in Tucson. Quote Link to comment Share on other sites More sharing options...
okent Posted July 23, 2021 Report Share Posted July 23, 2021 Ron, I had a similar problem with an ignition module that was intermittently going out. I wouldn't say it was running rough, but definitely different. We replaced the ignition modules and problem solved. Again, this happened only when the engine was hot. I'm sure that the guys here like Roger can get this figured out. Good luck. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted July 23, 2021 Report Share Posted July 23, 2021 Depending on what vintage engine you have and which ignition modules have I would look at what okent said. He is not the first to have this issue. I had a customer with the same thing. the modules fixed his as well. I think these were both with the early style non soft start ignition modules. They had issues when the EU switched to non lead solder. The normal failure is in the starting circuit, but there isn't any reason to think it couldn't happen in other parts of the modules. Quote Link to comment Share on other sites More sharing options...
okent Posted July 23, 2021 Report Share Posted July 23, 2021 Mine was an early 2008 model. Started that behavior last summer, so 2020. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted July 23, 2021 Report Share Posted July 23, 2021 My customers was also early 2008, and started about the same time. Quote Link to comment Share on other sites More sharing options...
Fr8dog Posted July 26, 2021 Author Report Share Posted July 26, 2021 The problem has been fixed thanks to Roger Lee. I'm sure you all know Roger. Well, he's come through again. After talking for almost an hour on Friday and not coming up with an answer Roger said, "one more thing, check the choke shaft for a punch mark tell me which way it's facing". I did (after I found the small punch mark) and the 2/4 carburetor choke was assembled wrong. Punch mark 180 degrees out. After the 5 min. it took to remove the linkage, turn the shaft and put the linkage back on, I ran the engine and it seemed to be fixed. Saturday I put the cowl back on and went flying. Everything was as it should be. Today I flew again and did everything I could do to make it screw up, including sitting on the ramp for 15 min. after flying, to let everything get hotter. I did another T/O and then a touch and go and then declared the problem fixed. There a lot of questions: how long has it been that way? There doesn't appear to be any reason the previous owner would have been into the choke in the 150 hrs. that he had it. Why did it the wait 30+ hrs. that I flew it? How did it run as good as it did? I am not knowing! Thanks Roger Quote Link to comment Share on other sites More sharing options...
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