How's your oil level? If it's down, it can take a while for oil pressure to build to fire the injectors. The healed situation may be attitude when parking affecting the oil pickup in the pan. That's just my 2 cents worth. I may be full of

 

Ah yes, the oil level - forgot to include that in my write-up. I did check the oil level during the long-start time period, and it was halfway up the hashes. I did not add oil. Also, it was long-starting whether I was parked on my driveway or in the street. The long-starts subsequently went away, so that should allow me to rule out oil level from the list of possible root causes... (I think...)

 

You also might want to check the oil level in the high pressure oil pump reservoir if the long hard starts return.

 

Hi guys, I’m back…and so is the no-start - I had another occurrence on 9/17/2025. It started cold just fine at home (and not a “long-start” either), went to Target, came back out, cranked forever, and nothing. Details and observations:

• Didn’t hear the fuel pump with key-on, but I imagine that could be because pressure was already reached (to rule this in or out next time, I put my length of fuel bowl drain hose in the truck so I can drain the fuel bowl and confirm that the pump indeed comes on when called for).
• Checked and changed the same relay I did on 5/1/2025 but no change, so maybe that wasn’t the root cause last time (just a coincidence?)
• Checked all fuses that sounded relevant - all fine.
• Left truck overnight, went back the next morning, and it fired right up (as I semi-expected based on the prior no-start experience where it magically fired later). Drove home normally (~5 minute drive, not even enough to get up to operating temp), parked, shut off, and re-started fine.

Got some logs from my DP-Tuner on the morning I picked it up at Target, but stupidly, I didn't have my tuner with me when either no-start happened so I don't have any data from those events. I quit leaving the tuner in the truck since I use the truck so infrequently and have had the tuner screen fail in the heat (I now left it where I’ll see it to grab it every time I drive the truck). Since it re-started fine the next morning, I was not able to get a DP-Tuner log of the no-start event itself.

I took four logs which turned into six files (see attached), but I’m not clear how DP-Tuner splits the logs into files so it’s difficult to provide the conditions under which the files were created. I am confident about the comments I added to the first file (e.g. key-on, cranking, started), but really can’t say beyond that. Maybe someone with more experience interpreting logs can make something of the data:

• 1st log: Cold start at Target on 9/18/2025. I observed ICP hit about 2,000psi max during cranking, then settled at about 800psi at idle. Is that typical?
• 2nd log: After having left the parking lot and cruising along on flat ground.
• 3rd log: Accelerating gently from a stoplight to 30mph approaching my neighborhood.
• 4th log: Re-starting at home after arriving and shutting down (it re-started just fine).

Summary of No-Start Failures

• Two no-start failures
• Both no-starts occurred when engine had already been run/warmed
• Has not happened from a cold start
• Has not died while driving

I don't know if an occurrence of N=2 is enough to make a conclusion, but are any of the systems such that they will achieve a required threshold when cold so it starts fine, then once running the requirement isn’t as demanding so it stays running, but then when you shut off and re-start while warm, it no longer meets the required threshold and won't start? I have a limited knowledge of the HPOP, but I could see it fitting this scenario and simply failing to achieve the required oil pressure to start the truck when warm due to thinner oil, but will do it when cold due to thicker oil.

Are there any sensors that only matter during a start? i.e. once started, the truck won't shut off even if the sensor is malfunctioning?

In the absence of root cause, is there anything easy/cheap to throw at it or check that COULD be related? Sensors, connections, and such? I’m not a big fan of moving forward without root cause, but if there is stuff that’s cheap/easy to check or replace before ripping into things, it might make sense.

Thanks for your input.

- Danny

 

What you likely have are Injector o-rings blowing out. When you have a no-start, check ICP, and IPR Duty Cycle. If you see a delay in ICP reaching 500 psi required for the PCM to fire the injectors along with a high IPR Duty Cycle (65% is max in stock tune) then it pretty much confirms injector o-ring leakage. It's harder for cold oil to get thru a leak space than hot, thinner oil, which explains why it will restart after a cool down period. Once the engine is running the HPOP is putting out enough oil to overcome the leakage and keep the pressure up. At cranking RPM, not so much (100-200 rpm cranking vs 650-700 rpm at idle.)
You can block off the HPOP hose to one of the heads (you'll need adapters to attach the ICP sensor to the driver's side hose) and crank to see which bank is at fault. If the engine starts and runs with one bank blocked off, then the leak is in that bank. But if you have any leakage in the injector o-rings, just figure on replacing them all.

 

Thanks. That explanation makes sense. I feel like it wouldn't be a stretch to also explain the prior long-starts. Perhaps coming out of "hibernation" (LOL), the leakage was a bit more pronounced due to slightly shrunken o-rings, hence the long-starts but ultimately firing. Then over the course of those next few days of driving the truck everyday, the injector o-rings reanimated a bit such that when cold at least, the leakage wasn't enough to cause a long-start and it would fire right up. But, when warm, the oil is able to leak by enough to cause a no-start.

I will drive the truck today to mimic prior conditions and see if I can get a no-start out of it and log the data. If not, I'll continue to do that until I do get a no-start. I gotta figure this out - can't just keep parking and not using it for fear of being stranded. I just won't shut her down until I am home!

It will be nice if I can confirm the o-ring leakage via your suggestion of looking for delay in ICP reaching 500psi and high IPR Duty Cycle.

Question: I am running a DP-Tuner 80hp daily tune, does that change what is considered a "high IPR Duty Cycle" and do you know what value should be considered "high"?

Any other symptoms I should be looking for? I haven't noticed any drop in power, no difference in exhaust output that I see, etc.

Thanks,
Danny

 

I don't know if the DP tuner 80HP tune would affect the high IPR limit. I may have the same tune.
But IPR duty cycle shouldn't have to go over 35% in any case for the engine to start.

 

Ok thanks, I have this info logged in my notes file.

Went for a drive today. Did not experience a no-start once returning home. It fired right up cold (no long-start), drove 20 minutes, parked it. Immediately cranked it and it re-started. Let it sit 30 minutes and cranked it and it re-started. Let it sit 1 hour and cranked it and it re-started. Will have to try to get a no-start another day...

I'll also check for codes every time I drive from now on. I'm a total idiot and saw some codes today that I assume were from the prior no-start on 9/17/2025, but cleared them before taking a picture or writing them down. That was really dumb. There is no dash light illuminated, these were only in the DP-Tuner. There were a number of codes: something like Accelerator Circuit something-or-other and some kind of pressure below desired. But I wouldn't know what they were even if you mentioned one. At least I know I have a blank slate moving forward and I'll be able to definitively connect code(s) to a given occurrence.

- Danny