Posting for a friend to hopefully figure out what is wrong with his truck.
2002 F550 w the 7.3-just over 200,000 miles.
truck has new injectors,new glow plugs ,new valve pan gaskets,new Hpop,new IPR valve,and new IPC
new fuel filters,fresh oil change.
New batteries and a new starter. Cranking speed is fine
have check fuel filter before trying to start cold and it is full of fuel
once started trucks runs great,

Problem is ,when truck sits overnight it will not start .glow plugs are heating,(I have checked them)
Gpr is working as it should.

The truck simply isn't getting any fuel.....during prolonged cranking it will not smoke in the least.
I discovered the other day if you cycle the key and fuel pump about ten times it will fire.

Hpop oil level on cold start is about 1/2 inch below top so thats normal
Also once truck has been started and run a few minutes it starts normally,just hard to start after it sets a ,,basically overnight.

 

It could be a fuel pump with a cold run issue...

I would still test the GPR again, and ohm out each of the glow plugs, and then with everything hooked up, ohm out the entire set of glow plugs (as one) from the GPR switched lug, and see if that reading makes sense. It should be a very low ohm value.

If you want help with the math, post each of the individual glow plug readings and the connected combined resistance. I'll crunch the numbers.

What I am thinking is that even if each plug and the GPR is good, the connection at the valve cover might not be. So they are not all really connected and heating.

I don't know enough about the 7,3 yet to point to other causes, but the symptom sure is in line with glow plugs.

 

Try plug'n ur in...i got weak batts and if truck aint plugged in and tender on batts overnight....forgetaboutit, she aint firing

 

Disconnect GP power at relay and connect amp meter. That will confirm GP operation as well as all connections.