I have a 2006 F350 6.0L, Intake, 5" Exhaust, EGR Delete, Sinister headers and up-pipes + y-pipes, head studs, and an SCT tuner. I run T6 synthetic motor oil, I have CAT ELC EC1 coolant in my truck. Oil temp never gets above 210 and coolant never gets above 205. The temperatures are always between 10 degrees. The ICP runs about 550 to 650 at idle and i have seen spikes around 4150 at full throttle, and normaly runs 1950 doing 80 down the highway. Outside temp has been between 85 in the morning and 95 to 100 after work plus the lovely humidity. My issue started about two weeks ago. When my truck sits for a few hours it will take about 10 to 15 seconds to start.(No Smoke) Ill drive to the gas station which is less than 3 miles away, turn the truck off, get what i need, come back and it starts fine. Ill drive 30 miles to work, shut it off, turn it right back on with no problems. 10 hours later when i get off it will take 10 to 15 seconds again.(No Smoke) I dont have any codes except for "tire/axle ratio out of acceptable range". but thats been there since i got the truck. What i believe is causing the issue is somewhere in the fuel rail pressure. An internal leak somewhere is my guess. I do not have a way to test my fuel pressures. Before i go blow money on guessing games, am i at least headed in the right direction?

I ordered the Blue Spring Kit from XDP.com. Should be here Wednesday. Thats the only thing i have purchased to maybe fix the issue.

 

Do you have fresh fuel filters?

Things to check after the 10 hour sit would be while cranking
FICM SYC
ICP Pressure
IPR

 

The filters have almost 5K on them. I hope they're clean still...

FICM Voltage never goes below 49V

ICP pressures will have to wait till i can grab my computer from work tomorrow.

 

Ok. I was referring to the FICM SYC, if it is staying 0 for the extended crank time, that could be the problem.

The SYC is basically looking for the cam/crank sensors to be in sync for firing the injectors

 

Well Snap-on didnt return my computer so ill be without it for another week...

Can my Edge CTS Monitor tell me about the FICM Sync?

 

Yes it has the pid

 

Well ill have it set up for in the morning then and ill see what i get.

 

I had the same issue and it wound up being the crank sensor wiring harness was bad, Check both Crankshaft sensor and Camsensor. The pig tail was bad on mine.