I am working on a 2001 f-550 with a 7.3l. It first came in because the o-rings on the injectors were bad and fuel was going into the oil. So we changed all the injector o-rings. It came back in shortly after running rough. It seems to run like a bear when it is cold and you first start driving. But as soon as it gets warmed up or you put it under a good load it acts like the fuel cut out and it skips and smokes terribly. If you let it set at idle for a while it seems to clear up, but will not run good until you let it set for hours or overnight. We replaced the ICP regulator and the MAP sensor only to switch them back out because they didn't make a difference.We ended up taking a peek into the fuel tank and saw some goopy stuff in the bottom. So, we cleaned the screen in the tank which was about blocked and changed the in-line pump on the frame which was packed full of gunk. We aslo put a new fuel filter on under the hood. The test drive went great!! The customer came and picked it up, and called back a couple days later saying it was doing the same thing. We told them to change the fuel filter cause we figured there was still some gunk in the line, so we ended up changing the fuel tank.
We now have this truck back in our possession again. Today I tryed to unplug the ICP for a test drive, did the same thing. I have been checking it out with a Snap-On Solus Pro scan tool. It seems to throw the ICP codes p1211 and p1280.
When it runs rough the cyl. contribution shows cyl. 8 fault. (Buzz test has always come back positive)
Someone mentioned on one thread to check the perdels. They normally run 0-1%. And typically cyl. 8 will run from 1-3%. But 8 was running a constant 4.3-4.4%. I am lost here. I am kind of thinking #8 injector?

All positive feedback is greatly appreciated.

 

With the gunk in the fuel system, did you replace the sending unit and clear out the feed and return fuel lines?

 

If you are getting fuel in the oil, then I would think you would have a split nozzle, or something severe getting fuel into the oil. Usually accompanied by white or bluish smoke that smells like raw fuel and burns your eyes.

Buzz test, all injectors sound nice and crisp?

 

Timmyboy76: I did not replace the sending unit or blow out the feed and return lines. It has had probably 4-5 fuel filters on it since. That sounds like a good place to start.

To BigAlsPSD: there is no longer any fuel going into the oil.

 

Today I blew out both the feed and return lines from the tank to the motor. I also cleaned out the inside of the filter housing. There was quite a bit of crap in the bottom. Then I took it for another test run and it did the same thing as it has been doing. When it was acting up I pulled over and let it run at idle for a few minutes. I revved it up a few times and it would cough a small cloud of black smoke then a larger cloud of blueish white smoke. Once I sat there a while and let it chill out it seemed to run better to get back to the shop. (When it is running good there is no smoke) I put the scan-tool on it when I got back and this time it threw a turbo code that said low or no boost. First time this one has been seen with this existing problem.

I did do another buzz test this morning and all of the injectors sound the same. "crisp"

 

What was the "goopy stuff" in the tank? Did it look like this?

 

It was similar in color (orange). But there was a lot more of it. Kind of like wet goopy orange paper. The stuff in the filter housing was dark and real fine. Probably just dirt that has accumulated over time.

 

Ya it was a red/orange color. The stuff you see in my picture is algae. Algae makes a mess in the system and it will keep coming back if you don't treat the whole system, but luckily it is very easy to fix. I ran PowerService Bio Kleen for 5 tanks of fuel and it cleaned the whole system up. Here is a picture of what my filter looked like


Not sure if the problem you are seeing is the same or not but I thought I would share a possible cause.

And my truck ran decent at idle but when you tried to drive it would run rough and the exhaust would burn your eyes like raw fuel. Then you let it idle for a while and it would be ok again until you tried to accelerate hard or go up a hill.

 

the tank is delaminating

 

The filter and the fuel both look clean, I don't believe there is an algae problem.

They have changed out the steel tank and put in a plastic tank since this problem arose.

 

Dang....I had seen that a couple times and figured that was it. I am at a loss

 

I really dont know much about diesels yet but would anything related to the CPS cause any strange things to happen? Im just basing this off other posts ive read where that was the culprit im not trying to flood the thread with BS tech but figured it was worth a shot.

 

Ok I finally figured it out. I did not take any pics during the process but here it is. Inside the take is the sending unit. On the sending unit there is a white plastic cartridge on the pick up tube. Inside of this cartridge there is two small thin cylinder shaped screens to filter the fuel. I took this apart and cleaned them up and the truck ran beautifully. And still is to this day. Thank you everyone for your input, put this one in the memory bank.

A dealer recommended replacing the sending unit due to this problem. I decided they could be cleaned just as easy seeing how the unit is well over $500.

 

Glad you figured it out! Many of us delete the Mixing chamber, here is a writeup on it.

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