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O.S. .61RF pumped engine problem --- Genius wanted

I have been into RC for 10+ years. Never seen such a problem with an OS engine. Engine is new (about 2 hours run-in) even if discontinued a few years back. Had to replace fuel pump as diaphragm had dried out... Installed a new Perry VP30 pump wich works fine and supplies lots of fuel to the type 86 carb. Cannot get engine to run rich to the point of completely unscrewing the needle valve. Engine is coupled to a MACs tuned pipe and header. Carb is free of restrictions. New O.S. glow plug no.8. Engine overheats and cuts out. As if something is preventing fuel from reaching carb. Can back pressure from tuned pipe be responsible? Anybody has an idea ?

Reply to
GN
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Check for air leaks, back plate , Head ect. mk

Reply to
Storm's Hamburgers

I've had this happen to me two times on my OPS's when trying to run them, once with a Perry, once without. With the Perry, it turned out I had started with the pipe too short. Without, I had a problem with another engine that surged badly, just wouldn't rev up or get rich. I'd stuck the wrong glow plug in it. In short, try a colder plug (I'd do that first since it's easiest), or a longer pipe. Subbing a smaller prop would have the same result as lengthening the pipe. I'm not sure what the compression is on the 61rf, but I don't have anything with a pipe that can run a plug as hot as a #8.

Reply to
John Alt

If this was the engine with the extra fuel nipple on the carb, you may have to replace the carb. I think that model interacted with the pump to monitor or adjust fuel presure in some way.

Reply to
Sport Pilot

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