My C7000 box truck had been idle for some time. I figured out that the old fuel pump was getting no fuel to the carb. I replaced it with one from Carid, I think, a year or so ago, too long to go back to them, if the new one is bad. My carb was getting fuel to the carb sufficient to run at idle. So I continued fixing other issues, as time allowed over the past months. This week, I drove it a 1/4 mile down the road, and the engine shut off, apparently getting no gas. Added gas to the tank (guage undependable) -- no start. Dragged it back to the yard. Pulled the inlet line and sucked gas from a can -- nothing to carb. Pulled outlet line and got a little spalsh of gas. Reattached inlet line to tank and got a similar splash of gas, still nothing up the tube to the carb. Blew through disconnected tube between pump and carb. all clear. I got out my nifty new Mightyvac Pressure/Vacuum tester. It works on my finger:) I got a nice vacuum on the inlet side of the pump. (I pumped up to 15#, and it held. With the return line clamped off, I got maybe 5-6# pressure on the outlet side that did not want to hold for long. With the return line disconnected, I attempted to plug that port and got maybe 1-2# pressure that would not hold. What could I do better or additional to diagnose this pump?