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I have a ST G21 .46 that I installed in a new Escapade. I can't get the engine to run correctly. I checked everything that Bax's tip mentioned as far as the Basic ST Needle Settings. The fuel Tank pickup is about 2 and one half inches lower than the engine needle valve. The Operating instructions that came with the engine says that the fuel tank pickup should be at the same height as the needle valve but that is not possible with this plane.
How much lower can the fuel tank pickup be than the needle valve before it causes the engine not to run right?

Bax

My Feedback: (11)

For almost all glow engines using straight carburetor suction or muffler pressure, the centerline of the fuel tank should be level with the center of the needle valve, or no more than about 3/8" lower. For the G21/.46 engine, you would not want to use a tank any larger than 10 ounces. An 8-ounce tank was commonly-used with that engine.

If the fuel tank is too low, you'll find that it will be difficult to get a good needle setting. That's because the engine will lean as the fuel level in the tank goes down. To keep the engine from being too lean at the end of the tank, it will have to be set too rich at the start of the tank.

With the fuel tank being so low, even muffler pressure won't help. You'd need to use a pump or crankcase pressure with a regulator. No needle setting will give you "clean" runs with the tank that low.