Please Help, Engine won't start!

[dufflespank]

After finally pulling my injectors, relapping the lapped surfaces, and putting everything back together, my '87 300D won't start. I've cranked for up to ten seconds at a time and not even a hint of the engine starting. Now, here are some observations:

The lift pump is definitely supplying fuel to the IP.

The Injectors are NOT receiving fuel from the hard lines.

The IP side of the hard lines DO see fuel; It seems as though the fuel is not being "pushed" up the lines and into the injectors.

I rerouted the fuel lines so that the fuel supply hose was pulling fuel from a gas can (just to make sure it wasn't a filter or a tank screen issue)

The spin-on filter is brand new



Now, the car started up right before this job was done (this was the first time the car had been fired up in months), so I'm pretty sure the IP is not
shot. Could this be air in the lines? Perhaps a bad IP? I would really appreciate any and all input, I really need this car running within the next few weeks, please help!