Fuel Pump/Line Help

Pipe thread is pipe thread. The pump is either pipe thread or it is NOT. I did Google pipe thread specifications and 1/4 NPT is indeed 18 tpi.

Is there a seat visible in the bottom? That would make it inverted flare, and 5/16 inverted flare is 1/2 x 20,

and a gasketed/ o ring fitting would also be that same thread (#5 which would be an odd size)

Frankly we are just guessing here. The summit add shows this pump as being 1/4 NPT. It either is or not. I'd be on the phone with Summit.