This is a very nice set up, people run it all the time. I agree with Donnie514, I would suspect carburetor is purcolating. Also, I try an minimize fuel routing in engine bay and or near the engine due to heat transfer, like the green setup in the picture. (Less cost, fittings, and heat transfer)
The main line coming up is usually close to headers, I wrap that as well or run it from inside fender well with bull head connectors to the regulator on the firewall. Moves it and helps keep it outside frame rail when you route it from the exhaust. Trouble spot is back by the tires/whee, rear well when going back to the tank.
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