Driving along today, and I got a dead pedal, then a puff of gray smoke and then dead. It wouldn't start after crank.
I towed it home & put a fuel pressure gauge on the Schrader valve on the VP44. It had 0 PSI during crank.
It throws codes P0500, P0234 & P1693.
So is it the VP44 or the LP?

 

There is a spot on top of your Fuel filter housing for a pressure check. Its just a plug, then check pressure there because that would be before your VP-44. IF there is no pressure there, your LP is dead. Hopefully, it didn't damage the VP-44. Good luck.

 

What was I measuring on the Schrade value just below the VP?

 

Unlike the 99 the 02's don't have the same filter housing. Measuring it at the Schrader valve is a good place.
Look at either replacing the LP or going aftermarket. Even if you VP is dead you'll need a new supply pump. Airdog is very good.

 

So if I measure 0 psi during crank at the Schrader value, does that indicate an LP problem? Or at least something other than the IP?

 

Bump the starter with the key and listen for the pump. It should run for 30 seconds. The pump doesn't run while cranking.

 

read this to help diagnoise

http://www.bluechipdiesel.com/vp44diagnostichelp.html

 

You can also loosen an injector line at the block and bump the starter. It should bleed fuel after a couple of times doing that. A fuel pressure gauge is a must, though. I have a cheapo mechanical one from Northern Tool (oil pressure gauge 0-30psi) that I tap after the boost pump (relocated to the frame rail). I can lean down and check it under my truck if there is any doubt. I also have the Edge Juice w/ Attitude which is great....