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Discussion Starter · #1 ·
I recently bought a 01 7.3 with 230000 miles. The previous owner sold it because he had an issue with it, and I can't figure it out either. When accelerating the check engine light comes on,and it does not start when warm. Testing showed warm cranking was only building 250-300 psi on the HPOP. Previous owner replaced ICP, IPR, and Cam sensor. I replaced injector O rings, and HPOP with a T-500. Issue still is there. Any thoughts? I'm out of ideas. Compression test showed 400-425 on 7, and 360 on 1. Also when letting off the throttle at low speeds sometimes it will die, and it seems underpowered. So all in all it still has a low HPOP pressure even though it has new orings and HPOP.
 

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What are you using to measure IC pressure? If you are going through the sensor, I would suggest swapping it for a known good one just for testing purposes. Watch IPR duty cycle like yan7gin suggested. Check all your pigtails. There just isn't that much in the system. There is a possibility your LPOP is fading and starving the HPOP while at idle and cranking. What is the code you are getting from the SES light?
 

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The only thing I might add is since the PO is the one who replaced ICP/IPR/CPS, do you know if he used after-market parts or genuine Motorcraft/IH parts?

Sometimes just because a PO said they did something does not mean it can immediately ruled out.

Good luck.
 
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How about the pickup tube sucking air also.
 

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That's a great thought. Diagnostics for that would include getting an oil pressure gauge hooked up and recording the pressure. Then add a gallon of oil, jack the rear of the truck as high as you can and repeat. If the pressure goes up significantly, then you've got a cracked oil pick up tube.

If the pressure is low and doesn't go up with the overfill test, then you've likely got a bad low pressure oil pump. Or your bearing could be shot. Or your bypass could be stuck open.
 

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Another problem T500?
Have to tried dead heading the hoses, giving ite ipr a straight 12 volts with an old injector pig tail?
This is in addition to the other good thoughts put forth so far.
When you installed pump, to what torque value did you tighten the drive gear bolt?
 

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Discussion Starter · #8 ·
I can't moniter the ipr, I had used someones tool to watch the pressures. The ipr was maxed out when trying to start warm. I had been using something that plugs into the obd2 port and transfers the data wirelessly to a phone. Check engine light showed P1249 P1211 and P1212. Not sure if genuine parts were used. Torqued drive gear on HPOP to 95 ft lbs. I read in the dealerships reports from previous owner about low oil pressure. So the idea of the LPOP would fit with that. How would you hook up an oil pressure gauge? Someone had told me about a pipe fitting around the oil filter?
 

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oilline.jpg

Attach your oil pressure gauge to the 1/8 NPT port shown in the above picture.
 

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Discussion Starter · #10 ·
I directly hooked up a gauge to the port and got a reading of 0 through all rpm ranges, so my gauge must be bad. I'll buy a new gauge and try again.
 

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Discussion Starter · #11 ·
Oil pressure with the new gauge:
right at start up: Idle 58psi. 1200rpm 66psi. 2000rpm 85psi.
Warm after 6 mile ride: Idle 19psi. 1200rpm 32psi.
And 2000rpm is unknown as truck just died so I need to wait for it to cool down
 

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Discussion Starter · #12 ·
Two more things. The eop sensor on top of the HPOP is basically striped out, and the oil level in the reservoir while warm is about an inch below the top.
 

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Check the HPOP level when it dies. If it's still full, you know it's downstream issue not upstream. The IPR solenoid can be heat sensitive. Works when cold - won't "grab" when warm.


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I think I'd try a different IPR since you know you did the orings yourself. Check all the pigtails as well.


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Discussion Starter · #17 ·
Tried a new ipr, and the problem is still the same. Unplugged the icp when warm to see if if it would start, and it doesn't. I should also note that although it's lacking power quite a bit, it doesn't lack power when it's cold.
 

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I would double check the injector orings. Maybe one is torn.
Also check the rail plugs.

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Just a thought, not sure but i think you should look at armature clearance!


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Armature clearance would make for a hard cold start and get better when warmed up. The OP said he swapped the O-rings in an effort to fix this and it didn't. New HPOP. New IPR and ICP sensor. You're out of options. Your truck is possessed.

Try shunting 12v straight to the IPR solenoid for a quick start up test. I'm wondering if there is something wonky in the IPR circuit that is causing a decreased voltage at the IPR when the truck is warm. Something like a sensor shorting out or a wire that only opens up when warm. Remember, IPR duty cycle is a report of what the PCM is requesting, not what the IPR is doing.
 
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