Run a temporary fuel line to the carb either from a seperate container or to the ON fitting on top of the fuel baffle.If it runs this way then your issue is with either the fuel selector valve or the fuel filter/seperator. If it still doesn’t take fuel on the direct line then it’s a carb issue
If it works with a temporary duel line it would be a leak ( sucking air ) or possibly a clogged fuel selector valve. Grey fuel lines are gone right? Are they 1/4” ID black automotive fuel lines?
Sorry, not sure what you mean here? I understand you have new fuel line but is the fuel selector valve already bypassed? Also check that the fuel lines are hooked up correctly, the fuel selector valve as well as the fuel baffle is embossed
Only check valves are the vent valve through the hull and pressure relief valve usually up top somewhere under seat roughly. These valves wouldn’t be your issue unless you were running for a few minutes and then problems arose. You can always just crack the fuel cap which will eliminate any issue with these one way valves
If it where me I would mix the fuel in the tank at 50:1 or mix the fuel in the seperate container besides the oil injection until you are sure the oil injection is working properly and set properly. It will run just fine even if it’s getting double the oil
Sorry, not sure what you mean here? I understand you have new fuel line but is the fuel selector valve already bypassed? Also check that the fuel lines are hooked up correctly, the fuel selector valve as well as the fuel baffle is embossed