ORIGINAL: TNRabbit
How about some details? What type of plane, setup, etc. Do you have any pics?
Are your fuel lines connected properly (vent/fuel inside tank)?
The size of the fuel line shouldn't affect it starting/running.
Sorry no photos.. Seagull PC-9.. The tank has the 3 prongs.. One on bottom with the weight going to carb.. one on top right going to filler and one on top left (which is bent up) to muffler.
Only other difference between the external tank and the on in the plane was the external tank was higher.. I was just thinking that there was not enough vaccum to get the fuel to the carb. Could it be the fuel tank isnt high enough?