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Old 03-06-2017, 11:22 AM
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Join Date: Oct 2006
Location: Cottage Grove, MN
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Originally Posted by MarkPrima View Post

I'm really confused with this issue. I just built a small airboat with a OS MAX 25FP and I mounted the gas tank (6oz.) below the motor but I am having trouble with the fuel siphoning and having to constantly prime the fuel line. Do people use something like a one-way valve in the fuel line?

How do you guys do this? I'm baffled.

Having the tank below the engine will likely siphon back to the tank unless you clamp the fuel line or close the throttle completely. The airbleed carb may cause it to siphon back regardless.

When the engine is running, the fuel should not siphon back due to the fuel draw of the engine. The only way to combat the fuel siphoning is to mount the fuel tank behind the engine ensuring the center of the tank doesn't sit above the center of the carburetor (spraybar). Do not use a check valve in the feed line - you will have carburetion problems.