ORIGINAL: Sport_Pilot
ORIGINAL: eddieC
Respectfully disagree there, SP. It's quite important, especially when there's little or no muffler pressure to help. I doubt it's the primary factor in the OP's case.
I have had inverted engines so low the fuel would run through the carb. I would clamp the fuel line with a hemostat prime the engine, start it and take the hemistat off. I had to turn the needle down a bit and the idle was a bit tricky, but as long as I did not fly inverted it ran fine. I have also seen tanks set real low, as long as you have muffler pressure,especially at idle you can get it to run. In fact one poster here has had tanks mounted about 6 inch's below the engine on an air boat and he was able to get it to run, though I thought it would be an issue that low.
I'm the guy with the above mentioned airboat. With the fuel tank 6" below and 1" behind the carb, the engine would draw fine. Farther away than that and you might have draw problems. On my boat, the engine ended up being 2" further behind the engine causing some draw problems. I had to run the idle needle a bit richer which required glow left on. I bought a pump to try.
I think the OP's problem is either bad fuel or mixture related. My inverted engine was getting too much fuel because of the over rich idle needle b