I have a 04 F550 w/6.0 after setting in -18 deg.weather it wouldnt start I figured fuel gelled I have now had it inside for 2 days and still wont start it cranks fine but no fire voltage at ficm is 49.2 volts it will try to fire with a short shot of either. vehicle ran fine till it sat out in the sub zero weather

 

Did you check fuel pressure? It could have lost prime.

 

yes fuel pressure was at 46 psi & fills bowl in seconds I think I have found the problem but the cause is still unknown. I removed the IPR from the HPOP and found the screen sucked into the valve,I will replace it today & post the outcome

 

Hmm