I just did a HPOP pressure test on my 1995 f250. Several issues but that's in another post. I have attached a short video of what I did. Before I run out and buy a new HPOP I was hoping that some one who knows how to do this can let me know if I've done it correctly or if I've missed something. Can the pump just completely crap out like this. Thanks

You didn't say if the IPR was plugged in or not?
I'm not sure which way you need to have it. But IPR could be bad.

Sent from my SAMSUNG-SM-G890A using Tapatalk

Yes the IPR was plug in and it's new with a new pigtail. I'm going to try and apply the 12v to it and see if it makes a difference, really want to be sure on that pump pressure, the truck was running with the new IPR , I shut it off then that was it haven't been able to start since.

Ok, I applied 12v to the IPR while cranking and the gauge shot up to 3500 psi , I assume that high cause it's dead headed and no place for the oil to go and not cycling. I checked ohms on both the new IPR and the old IPR and they were the same at 10.4, how do you know if you have a good IPR? And can I assume the pump is good ? Also If the IPR shut when the 12v applied does that mean it's good and it's not getting the proper signal, maybe bad wiring? Learning as I go an appreciate the help. Learning as I go an appreciate the help.

Well you know the pump is good, as it built 3500psi, and the IPR is actuating with 12v applied to it. Can you check IPR percentage while cranking?

Yes I was getting 65% & only 200 psi at the ICP while cranking before I hooked up the pressure gauge, then after I hooked up the gauge and without the 12v applied I only had 200 psi on the gauge and the IPR was still showing 65% while cranking.

I've never tested a HPOP that way...I always pulled one of the dummy plugs out, hooked up my gauge and tied it off to the mirror or something on the cowl to watch it. Then I go out drive down the road on the biggest tune the truck has, if its tuned. stock I've always done the same way. but get up to about 55 mph and hammer it to 90 mph. it'll spike with a max and it will level out with a constant number. I've done it on about 25 different trucks this way and the best number I ever saw was 2300 psi and the worst was 1750 psi. I've always been told a healthy pump should level out with atleast 2400 psi. as for the IPR, check the wiring. I had one truck that had a new hpop, new ICP and new IPR and the IPR pigtail had a rubbed wire in the loom causing it to ground out, wouldn't run at all until you wiggled it. luckily the IPR pigtail is only about 6 bucks as its the same as one off the 6.0s for the VGT solenoid

I can only test cranking as the truck won't start, I've changed all the pig tails , ICP, CPS, AND IPR . Seems to me if I have the pump dead headed and get 3500 psi at the gauge pump must be good and the signal to the IPR. Is screwed up somehow
As I only get 200 psi cranking when it's all hooked up. Just don't know what that somehow is.

If your getting 3500psi when dead headed, and 200 when hooked up, I'd say 1 or more injectors is pissing oil. Pull the valve covers and crank it over.

I know you just replaced the icp but did you try cranking it over unplugged?
Got this from another website that comes right from the manual

Pressure control in the injector control pressure system is closed loop. It is controlled by the injection pressure regulator (IPR), the injection control pressure (ICP) sensor and the strategy in the powertrain control module (PCM).

The IPR is a pulse-width modulated valve operating at 400 Hz. The pulse width is modulated from a duty cycle of 8 to 50% to control injection control pressure from 3.4-20.7 MPa (500-3000 psi). The IPR is mounted in the high pressure pump and achieves injection control pressure regulation by discharging excess oil through a shuttle valve into the front cover and back to sump.

The PCM controls the injection pressure regulator (IPR) by an internal ground switch (low side driver) internal to the PCM. Pressure control is a variable function of the engine control strategy and the calibration that has been programmed into the PCM.

The injection control pressure (ICP) sensor is mounted on the left cylinder head and is the feedback signal for the closed loop control system. The ICP sensor is a ceramic disk-type pressure sensor that converts pressure into a 0 to 5 volt analog signal that the PCM uses to determine injection control pressure. Typical operating range is 0.7 to 3.2 volts.

A spring/piston pop-off valve is installed internal to the high pressure pump and is set to discharge oil pressure into the front cover in the event injection control pressure exceeds 27.6 MPa (4000 psi).
If you hook up the scantool, and monitor ICP (psi) while cranking...you'll see IPR% (duty cycle) climb & climb 15% key on..20, 30, 40, 55%, higher..the increase in IPR% means that the PCM is requesting ICP pressure to increase...

so ALSO watch ICP(psi) and if it comes up to only 180-250psi or so and stays there...then it's the IPR hung open (bypassing oil back to the oil pan through the front cover) such that only minimal psi can be made.

If the ICP is VERY low...like under 60psi...then it could be injector (poppets) pissing oil (under the VC's)..which is typical for injector with more than 180-200k miles.

if ICP climbs above 550-600..then it will probably climb much higher (15-1800+) and it is most likely going to be an electrical issue.