Lift pump is new. I changed it about 6 months ago.
As Jack inferred, besides the possibility of your 6 month old lift pump simply failing (the OEM Carter pumps are notorious), there are a half dozen other reasons why it might stop running not the fault of the lift pump. For example, the lift pump is powered directly by the ECM, and occasionally we hear about an ECM which fails. You could have a wiring problem, etc.
It's best to eliminate the basics and most common problems before you attempt to test the VP44 on the truck, this is why I recommended you verify that you have adequate fuel pressure. Replacing the fuel filter was a smart move.
Once you verify the fuel pressure is adequate, the next step would be to make sure excessive air isn't trapped in the fuel filter cannister and fuel supply line leading to the VP44. This can be accomplished by loosening the fitting at the VP44 fuel inlet, placing a suitable container under this fitting (small coffee can, etc. ), and then activating the lift pump again until a steady stream of fuel comes out of the fitting. Tightening up the VP44 fuel inlet fitting and then try starting the engine again after loosening 2 or 3 injector lines to purge air from them (sounded like you already know that technique).
If you still don't have any luck, you can CAREFULLY hot wire the VP44 by doing the following:
Disconnect the VP44 wiring harness connector completely.
Connect pin 6 on the VP44 to battery ground.
Connect pin 7 on the VP44 to battery positive.
A diagram of the sockets on the VP44 wiring harness connector is included below. The pins on the VP44 will be the reverse of this diagram (a mirror image). Make sure you know which pins are which... numbers are molded on the connector and possibly on the VP44 (I can't remember). You must insure you don't cause any short circuits or make connections to the wrong pins on the VP44. I would also strongly advise you to add a 15 amp fuse between the VP44 and battery positive.
As soon as you make the last connection the VP44, it will be ON and ready to go. Attempt to start the engine in the normal manner. If everything is working properly, the engine will immediately start and idle and do nothing else. Be aware the accelerator pedal won't work and the ignition key won't shut off the engine once started. To shut off the engine, you'll need to pull the jumper wire from the battery positive terminal.
Also be aware that by doing this you'll have a bunch of DTC's (Diagnostic Trouble Codes) set in the ECM and PCM and the check engine lamp will be lite. You'll need to clear them all with a code scanner afterwards. No harm done... just wanted you to be aware of it.
Good luck!
John L.
Attention: TDR Forum Junkies 
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