What Would Keep the Fuel Pump From Pumping?

[cgrossl]

I have an 85 Chevy SWB, 2WD with about 150,000 miles on the original 305. Over the last month or two, I have noticed that every now and then, it randomly acts like it is running out of gas. It would do this for a few seconds then go away. At first, this happened very rarely. Over time, this problem got worse. It started happening more frequently and when it did happen, it happened for a longer period of time. Finally, I decided it was time to look into it.

The first place that I thought to look was the fuel filter so I replaced it, no change. Then, I replaced the fuel pump. After replacing the fuel pump, it isn't pumping a drop of fuel. I can manually fill the float bowl with gas, and the truck will run about 30 seconds, just fine. While it is running, I can completely disconnect the fuel line and not a drop of fuel comes out. This had me completely baffled. I thought, maybe the fuel line going from the tank to the pump is clogged. So, today, I disconnected it from the pump, then shot compressed air into the tank. Fuel spurted wildly all over the floor. Definitely not clogged. But, I tried running it again anyway, no change. I should also mention that when I replaced the fuel pump, I checked the oil and it didn't even register on the dipstick. But, I am still getting oil pressure.

I figure that I have one of two possible problems,

1. The new fuel pump that I bought is defective. I don't think that this is very likely though,

2. Due to the low oil level and high mileage, the fuel pump lobe wore off of the camshaft. I seem to remember reading somewhere that engines of this era were bad for that.

Am I missing anything? Is there something else that could be wrong?