2005 F450 6.0 no start

[onestopad]

I have a 05 F450 in my shop, we started with having the inj rebuilt, then the high pressure oil tubes and dummy plugs replaced. Also replaced IPR valve and ICP sensor. The hpop was leaking so we replaced it and still only 333psi. The FICM is doing its thing, but no codes and no start! Im lost on this one, any ideas?

[dazdillenger]

Cracked branch tube is the most likely suspect if you've replaced the STC fitting, standpipe o-rings, hpop, and dummy plugs.

[onestopad]

how likely are the branch tubes to crack?

[dazdillenger]

If you have replaced (correctly) all of the above, there can't be much left. Have you verified the LPOP is supplying proper pressure/volume to the HPOP? Pull the oil filter/cap, depress the button, and have an assistant crank the truck. It should fill the resovoir within 5-10 seconds. If it doesn't, or is aerated, look at the supply side. If it does, then the branch tube is likely broken. I had an 04 that the right side broke off completely. It isn't unheard of.

[onestopad]

We already checked out the lpop and the res. fills up fast. The oil pressure gauge also come up quick while cranking. Time to check the branch tube, thanks! Do you have any easier tips to replace it, or trick of the trade?

[dazdillenger]

I'm sorry to say replacement requires removal of the transmission, and the rear engine cover. Not an easy task by any means. Have you tried pressurizing the oil system, commanding the IPR closed, and listening for leaks?

[onestopad]

I did try to apply shop air through the ICP sensor port, but I have a SNAP ON MODUS, and MATCO INTERCEPTOR and they wont command it closed unless there is another way?

[dazdillenger]

get a pigtail, or cut yours off. Applying 5 volts to the IPR should command it to close 85 percent.

[onestopad]

I read somewhere that applying direct voltage for longer than 120sec would damage the IPR valve? The system should hold solid? no air whats so ever?

[dazdillenger]

30 seconds is as long as I would do it, that seems to be the golden number. You can repeat if necessary, just let it cool down. It is just a coil after all, once it cools you're good to go.

Purge all the oil out of the system first-do this by pressurizing it with the IPR open. once you hear air rushing, command the IPR closed and listen for leaks. You may need a stethoscope if they're small, but only building 333psi sounds like a fairly large leak. What duty cycle are you seeing when trying to start? At 333psi, what is the IPR duty cycle?