Nissan Truck Fuel Pump Relay

My Fuel Pump Is Intermittantly Cutting Out Causing Missing And Killing Engine. When This Happens Dark Smoke Is Noticeable From Tail Pipe...

Why Will My Fuel Pump Not Work,everything Looks Good,took Fuel Pump Out Hooked It Direct To Battery And It Works Relay Has Been Replaced...

Replaced Coil, Fuel Pump/filter, Fuel Relay...idles Great, Takes Off Good, At 35mph Starts Bucking As If Running Out Of Gas...let Off Gas An...