Long crank and touch start

Smokin 6.0 · Apr 5, 2021

Got a 99 7.3 that I’m having starting issues with I have a snap on scanner I’m using and what I’m seeing is 450-510 icp pressure and 37% IPR at idle and when you take off the icp goes up around 800 psi and then the ipr is around 50-60% at wot I’m seeing 1100psi icp and it starts dropping but the ipr is instantly at 65%.. any ideas ? Thanks

psduser1 · Apr 5, 2021

If you can swap in a known good ipr, just to check, but my first guess would be a failing hpop.
Miles on unit, maintenance, all play a role, obviously, but low icp at wot generally indicates a weak pump, or possibly failing injectors.
Faulty injectors have other issues, though, along with hard starts.
Really need a bit more detail for an accurate guess, lol.

Smokin 6.0 · Apr 5, 2021

It’s got 268k and I believe it’s all original parts. Looking at it for my cousin. I can try a good ipr and see what that does. Before I get under the valve covers would I be ok to say there may be a injector oring failure ? I buzz tested the injectors and all sounded ok so I’m assuming the valve cover gaskets are fine

psduser1 · Apr 5, 2021

Its not impossible, but at that mileage on original parts, injectors are probably right behind the pump. Probably not an oring failure.

I say a candid discussion about how long your cousin expects to keep the truck is in order.
As in, injectors are expensive, lol. Maybe pull the injectors and have them flow tested? I think unlimited diesel charged me 250ish for the last set for a flow test?

Smokin 6.0 · Apr 6, 2021

I’ll do alittle more investigating and post back. Thanks

ghohouston · Apr 6, 2021

I'd say you have a high pressure oil leak, so probably injector o rings. Check the fuel filter to see if it is black. If no issue is found with injector o rings, injectors themselves may be bleeding off high pressure oil.

Smokin 6.0 · Apr 6, 2021

I wondered that aswell. I have a ipr block off that I’m gunna try this weekend and see what my pump pressure is deadheaded. Here’s the other thing when I pull the icp when it’s running it dies and with the truck off if you pull the icp it will crank but never fire.

Addicted4 · Apr 8, 2021

Interesting post as my truck was having issues building over 2200psi at wot, had my pump turned into a t500 and then it would build 2500psi. Couple months later now it’ll build 17-1900 for a brief second and drop to 900-1000psi at anything over half throttle. Cold and hot starts it has no issues, duty cycle % is 8.5-9% at idle when at operating temp. I ordered injectors cause that’s what I hope the problem is but could still be an ipr or pump issue. Also I went hybrids for the sake of hpo consumption and I only want 350hp solid tow/dd

Smokin 6.0 · Apr 14, 2021

Update... I put a ipr block off plug in and truck will build 3400 psi cranking.. HPOP is good. I pulled the ipr and bench tested it and it appears to be stuck wide open. I installed a new on and the truck will build up to 2600 psi at wot now.. still cranks awhile to fire it up. When I first got it back together the snap on scanner was saying 700-750 psi icp pressure when idle after it warmed up the icp dropped to 500-550 at idle I looked at my PERDEL and cylinder 1 is at 1.7.....2,3,4,5,6,7 are at 0.0 or no higher than 0.9 but cylinder 8 is 5.9 to 7.6.. I think I have a issue with that injector maybe not contributing much or completely dead anybody got any ideas ?

psduser1 · Apr 15, 2021

Good deal on the pump!
Sounds like your numbers are reasonable for the mileage. Id still shop for injectors, as they are definitely worn.
The long crank may get better, if there is still some air on the oil side. It takes a few miles/hard pulls to refill oil galleys completely. If it doesn't get better, I'd still chalk the long crank to a poor spray pattern.