My 96 psd is running rough all the time now. I was told to replace the ipr but first to check other things would be wise. Plowhand told me to disconnect the the icp, wait a minute and the pcm would go into default. If the engine smooths out then it is bad. my question is which one the icp or pcm? and where are the two located at?

 

Toward the front of the engine on the inside(valley or inboard side) of the driver's head. Injection control pressure sensor. Unplug it and if the truck runs better then replace the sensor itself. May or may not solve your problem. Let us know what happens.

You may want to take a look down behind your (HPOP) high pressure oil reservoir and pump on top of the front of your engine just in front of the fuel filter and down in low a little. There is a (IPR) injection pressure regulator down in there with a two wire plug on the side of it. On the very end of it there is a stamped steel nut that holds the spacer bushing and the solenoid on it. Reach down in there carefully and see if it is tight. If not gently tighten it with needle-nose pliers. It needs to be kept tight so that the solenoid is locked in one place and accurately reading the oil pressure that is being generated by the HPOP. This tells the (PCM-powertrain control module) computer that there is enough oil pressure in the system to fire your injectors and then the computer tells the (IDM) injector driver module to go ahead and fire the injectors in the proper sequence and at the right time(according to information obtained from the (CPS) camshaft positioning sensor). It sounds complicated but it really isn't.

The IPR can create a no-start situation but it can also create a fluttering rough running condition if the nut is loose and the solenoid is moving a little tiny bit continuously so the computer is not getting a crisp, clear signal about the fuel injection oil pressure. When your engine is warm and you have difficulty with a warm restart it is usually because the o-rings on the IPR are leaking a little bit(cut,torn or worn) and the warm, thin oil can not generate enough oil pressure quickly and steadily enough for the IPR to send a steady signal to the computer so it does not tell the IDM to fire the injectors so your engine gets no fuel injected into it and it won't start. If it starts normally when cold but is a hard start when hot it is almost definitely IPR o-rings.

 

disconnected the ICP...nothing. I am not sure if I knoe exactly what you mean by the solenoid. Do you mean the end of the ipr itself? One thing I do know for sure is when I cranked on it, it appeared that smoke came from atop the engine. Hard to tell it did not smell like smoke or burning wires. I will look over the wires a bit more in the morning.

 

I was thinking, could it be air in the fuel system? When I bought it I changed the filter. Just took the old one out and put the new one in. Are you supposed to bleed the air out?

 

A fuel fiter change wont get air in the lines, but if it did it would automatically bleed the system

 

If I choose to replace my ipr there is one on ebay but it is for a 94 mine is a 96.. Would they be the same even with different part #'s

 

The pump# is what you need to go by when ordering an IPR. Notice where is says "All Years ???" latest part numbers. Kinda Confusing.

Maybe all you need are the o'rings.
Here's a bunch of IPR part #'s.

IPR Connector with 12" Pigtail
(International) 2501107C1

IPR O-Ring Kit (for when IPR valve replacement is not required)
(Ford) F6TZ-9C977-AN (F6TZ-9C977-AA?)
(International) 1825806C92 (1825806C91?)

IPR Injection Pressure Regulator
(Ford) F4TZ-9C968-C (engine serial no. 187099 & before or pump no. 255C92)
(International) 1824982C91 (engine serial no. 187099 & before or pump no. 255C92)
(International) 1833798C91 (All Years ???) latest part number
(Ford) F81Z-9C968-AA (engine serial no. 187100 & up or pump no. 247C91)