I'm working on my brother's 7.3L that long cranks before starting (20 seconds typically), diagnosing with Forscan and viewing the IPR % values along with the ICP Pressures. It shows zero ICP pressures while cranking the first 20 seconds, the IPR will go all the way to 65% (wide open) while cranking, once pressure shows up on data, the truck starts and idles fine (700-850 psi at idle). The HPOP reservoir does not drain down at all even after sitting for a long time but it seems like the oil galleys in the heads are losing prime possibly, or maybe an injector o-ring is leaking slightly. This issue will repeat itself within five minutes of shutting down the truck as well. It fires right back up fine if you start it withing 30 seconds of turning it off.

Is this a typical injector o-ring issue?
How else can those oil galleys not show a little pressure right as you start to crank? The HPOP has it's own reservoir and the HPOP was recently replaced.

 

Have you noticed if the oil level is going down any? You could always do the cody test and pressurize the HPO rails with air . Wonder if maybe the oil galley drain plugs blew an o-ring?

 

Oil level has not changed at all and there are no visible leaks on the engine anywhere. Very clean engine bay.

 

Did this problem occur before the new hpop was installed? If it's not using any oil then I wouldn't think it would be injector o-rings, I know when I lost an injector o-ring I was using quite a bit of oil.
Is there oil in the icp connector?
Maybe try disconnecting the ICP sensor to see if anything changes

 

The problem was there before the hpop was installed. The hpop was suspected to be the issue, and it turned out to not fix the problem.

This truck went to three shops and they all tried to throw parts at it without any luck actually fixing the starting issue.

 

This is something I rigged up to put shop air to the HPO lines going to the heads, just disconnect a line from hpop and screw it on to this and pump it up with air. This is for JIC fittings but if you have the original quick disconnect fittings you can drill and tap an old fittings if you have one around. Other guys have had luck just putting a blowgun straight into the HPO fitting on the head and holding it there injecting air in but I have a hard time doing that so I rigged up this contraption. Seems like it's either an electrical issue or you have some kind of very minor leak that is allowing the oil galleys to leak down when engine is off. I'm sure others will be a long shortly to offer some additional advice

 

I was thinking of this too. Seems that within the last year or so there’s been a couple guys with internal head plugs leaking HPO. Something to check anyhow. Seems like most plausible cause based on the investigation steps and conditions.

 

So, I just tried putting shop air into the injector line ports in the head. I used the rubber tipped blow gun approach. Both sides seem to hold pressure but I'm not applying that much pressure I don't think. When I let off the pressure on the blow gun, an audible hiss of air pressure relieves. Do I need to apply 100+ pounds of shop air to that galley to actually test the o-rings?

 

This is awesome. I think I may be taking a visit to the hardware store tonight.

 

Yes you will want to apply as much air pressure as possible, realistically 150 PSI is nothing compared to The 3000 PSI the HPO system can see. This is why I like the contraption with the ball valve, you can close the ball valve to see if it leaks down.
Ball valve also aids in relieving the pressure, forgot to close the ball valve one time when disconnecting the shop air hose... That didn't turn out so well lol.

 

we got ourselves a mock up. I guess we need a higher range gauge though.

 

Wow that was fast! Different gauge would probably be better. Does the truck have stock injectors, chip/tuner?

 

This truck has a DP Tuner with single shot injectors. My brother says they are "equivalent to what they put in medium duty trucks, just a little more than stock".

 

Okay, both heads will hold 140 psi of shop air. No leaks to be heard at all. After letting it set for about fifteen minutes it went from 130 to 90psi. Slow leak?

 

Was this issue present before the HPOP replacement?

Is it possible the HPOP gear is slipping?