Originally Posted by mauryr

That looks like tygon hoses used in festo QS connectors. While that may or may not be the cause of your unexpected shutdown, qs fittings are secure only when used with polyurethane tubes. You also do not want sharp turns such as the one you have between the uat and the fuel tank, make a big loop instead.
I am not sure I understand your fueling connection so I won't comment on that, save reminding you that you cannot use a one way check valve because the vacuum caused by the pump would open it and let air in.
Good luck fixing your issue!