N14 Celect fuel check valve

If truck hasn’t been started in a couple days, it will start, run for about 3 seconds and either die or cut out. If it dies it will crank a little longer and start fine. I looked for check valves on both sides of the cooling plate and for one at the line going to the pump but none are check valves. Any idea what the fuel pump or system is using to not allow fuel to run back to the tanks? I was of the belief that all the N14’s used a ball style check valve at or around the cooling plate?

 

I was wondering what this is used for on the 90* fitting going to the pump?

 

This engine used to not do this, so what likely causing this? I change the fuel filters probably more often than necessary and it’ll start by just bumping the key. Batteries are less than a year old.

 

If I start it everyday, that’s basically 10-11hrs straight it’s running and 13-14hrs, it’s setting. Most of the time there’s no flutter at the 3 second mark after start up but sometimes there is but generally never dies. It will die, if it’s not been started in several days or longer.

 

It runs one filter which is a filter/water separator but not sure if it’s a Davao.