Hey, Im new to the forums on the posting side anyway, I have relied on them in the past for my other trucks, so thanks for all who have contributed! Ive been searching hard for a thread that has symptoms my truck. So heres another thread...

I have a 2000 F250 7.3 4x4 with 180k on the clock. Ive owned it for a year and a half and its been really great to me. This Monday after completing a 600 mile or so trip for the Holiday with no issues the day before, as I was driving around 40mph in town under normal conditions-no load, the truck sort of stuttered at 1800ish Rpms. Its hard to describe the shutter but seems like the truck breifley shut off for less than a second. It did that about 3 more times under consistent light acceleration over the course of a couple minutes. Pulled over and looked for anything leaking and checked tranny fuild, no issues there. Truck didnt act up again until later that night, had a very brief stutter occasionally. Its very hard to even make it happen consistently. It also is surging at low acceleration in the 1500 rpm range. It will jump up only about 200ish rpm and back down and isnt real consistent in it doing this either.... It will do this with cruise on as well.

So heres what I have done since Monday: Changed the CPS, there was already a grey one in there. No change. Changed the fuel filter, I knew I was over due on this one any way by a few thousand miles. I changed it almost a year ago and about 15k miles. The filter was very dirty and there was a fair bit of sediment in the bowl. I cleaned it out, flushed with diesel and put the new filter in and added diesel kleen to a mostly full tank on wednesday. It has been running noticeably better. The surging is still there-sporadically and the stutter is more sporadic as well. Im certainly no mechanic but I do try to do what I can within reason, Ill usually stop if I have to tear into an engine-just not comfortable there. So Im thinking ive got a fuel issue? I know those screens in the fuel pickup can get clogged up and neglected, ( I have no idea if the previous owner has touched those) but I would imagine that would be more consistent lack of fuel.

Here is what I know about the truck from the previous owner:
December of 2015 he had the frame mounted fuel pump replaced and they dropped the fuel tank-dosent say why or if they did the screens.
He replaced 5 injectors and did the o-rings on the other 3-kinda stupid if you ask me and have no record of which ones were done
Replaced fuel pressure regulator and ICP

Since ive owned it my mechanic has done:
This summer replaced injector 3 & 8 -they failed compression test-hoping they were two of the three he didn't replace
Replace IDM and Under Cover Harness
Transmisson service-not a flush

Any help would be greatly appreciated.

 

Two things that come to mind right away is what was/is the fuel level in the truck (related to Hutch/Harpoon mod) when it is falling on its face and the Throttle Position Sensor (TPS) might be acting up.

 

The fuel level has been above 3/4 tank. Ill see if there is any changes with a lower level of fuel in the tank. Yes ive thought about the TPS as well. I'm going to try it on cruise control today if its acting up again.

 

Sounds like my issue this summer. Unplug the icp sensor and check the pigtail and inside the plug for oil

 

Also, not sure what the hutch harpoon mod is? As far as I know, the truck hasnt had that mod. Its pretty much stock with the exception of an AFE performace air intake he did. Just cleaned and oiled the filter.

 

I assumed you were aware because you made reference to the tanks internal screens being clogged. The Hutch mod is where the internal tank screens are removed and an external screen filter of some sort is added. This allows for easy filter cleaning and removes the air being pulled into the fuel system. The Harpoon mod is where the fill tube in the tank is trimmed to just below the surface of the tank to allow for faster fuel filling and more fuel into the tank.

 

I would agree with this. I would think that it is either the IPR or Icp sensor. If unplugging the icp works, then that should be your problem. If it does not fix it, I would guess the ipr. The IPR is easy to rebuild. I am by no means an expert on a 7.3, but when I finally got my project running late this summer, it would do what you describe when it warmed up, but mine was bad. I rebuilt the IPR, and it all but went away. It did go away, but it came back about a thousand miles later. My IPR was pretty dirty when I rebuilt it, so I ordered a new one this week, and I am waiting on it to come in. Hopefully it clears everything up. I have already replaced my icp sensor with a motorcraft one, so I don't think that is my problem. On top of that, I caught it on autoenginuity, and the duty cycle is bouncing on mine when it does it, but the injector pressure stays pretty steady. The idle pretty much follows the duty cycle up and down. If I floor it when mine does it, it puffs black smoke and kinda clears up the surging. Mine only does it on a partial/light throttle, such as keeping a steady speed either in town or on the interstate. I drove about 200 miles the other night, and I had two episodes that lasted 5-10 ten minutes each. My theory on mine is a bad spot on the little needle in the IPR that sticks every now and then.

FYI, if you don't already know. Motorcraft/International sensors are the only way to go on these things. The guy that I bought my truck from had replaced a lot of stuff(not just sensors) with parts house parts. I know that he did, because he showed me the receipts. I ended up having to replace a lot of the parts with oem to get it running right. I love OEM parts, but I don't know if I have ever had a vehicle that basically had to have them or else. If your local dealers are severely overpriced like some of the ones I have had to deal with in the past, there are a lot of online dealers that sell them for a fair price.

 

Ive been reading up on the related fuel issues in the 7.3 so thats how i was aware of the screen issues. I like the idea of the hutch/harpoon mod if I need to get to that at some point.

For the ICP sensor, you're recommending unplugging the pig tail and running the truck to see if the issues go away? And removing the ICP later and checking for oil. Just want to make sure im picking up what you're throwing down.

Update: drove the truck into town today, about 15 miles. No stutter but there was some surging present. Almost as though its beginning to heal it self. Maybe some bad fuel? Ill see what happens I guess.

 

I can't say from experience because I replaced my ICP sensor because it was the wrong part when I got it. But from what I have read, if you suspect the ICP is bad, there are two things that are pretty good indicators to confirm your suspicions. 1) Oil leaking into the pigtail through the sensor 2) running the engine in a default setting by unplugging the sensor, and the miss clears up. I have never experienced either of these, this is just repeating what I have researched on this and other sites.

 

Well, the unplugging it to run part is if it will not start at all and you unplug the pigtail and then it starts it's definately a bad sensor or pigtail. Shouldn't drive without it plugged in from what I've read. The surging, stuttering, dying and instantly being able to restart can be the oil blowing thru the seal in the sensor and causing problems with the voltage readings. It's just a very easy thing to check, unplug the sensor and take a white paper towel to the pig tail and inside the plug to check for oil.

If you can run ForScan while driving and it stutters and such and you see your ICP default to 750psi you know the sensor is dying.

Do not remove the ICP sensor and attempt to start the truck. You will spray high pressure oil all over everything under the hood

 

Just unplugged and checked the ICP, no oil in there what so ever. Pigtail looked fine too. Just took the interstate home, going about 70 with cruise on, Had a bit of a surge but not really bad. When coming down from highspeed to lower speeds (exiting the freeway) the truck sort of sounds like its dying, kind of gets relly quite and seems like its missing ( not really sure how to tell a misfire) then returns to a normal idle. Its done this since ive owned it and i guess never really seemed to be too concerning.

Any other signs of the ICP going bad? like i said earlier it was replaced just 2 years ago....

Did I miss anything with the CPS?

 

As long they are Motorcraft brand. Other brands cause about as much trouble as they initially fix

 

It was the napa brand. ( all i could get that morning). It looked like it had been replaced before too as it wasnt the black one. Not quite sure where to go from here. Fuel pressure check? what is the ForScan?