Plumbing is not correct. Double check to make sure the check valve is attached in the proper line and in the proper direction. Then make sure the plumbing matches the diagram. I think you likely have plumbing messed up...they just don't dump fuel like that..

If the regulator was staying open all the time the fuel would run from the carb not the muffler.

The enigne should likely not need any prime to get it started...maybe if its been sitting for a long time....


Inverted mounting has no effect on these engines. If they are upright you might be able to run them a little richer at idle that if they are inverted that is the only difference upright to inverted mounting.

Troy Newman
Team YS