7.3 runs horrible after a decent drive.

hucorey

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It's pretty rare I ever post with issues, but....lol. I have a very problematic redheaded stepchild customer truck in the shop and it's very odd problem.

Truck only runs really bad after being driven for about 25 miles or so. Runs flawless up until that point. I'm not sure if it's a heat soak issue into an electronic device/sensor or not. After the 25ish miles driven, it completely falls on its face to the point it stalls sometimes, acts like it's running on less than 4 cylinders. I mean it's really bad.

This is what I've checked/changed.

-Injectors were indeed bad as perdels were showing 3 fairly weak and 3 others questionable. Buzz test also showed 6 were a bit quiter.

-Found a bad pass side UVCH (Dorman) grounds were bad at the splice. Installed a known good gasket I had and a new Ford harness. Originally had codes for #1,#3,#5 CCT failure. Codes went away after gasket harness swap.

-Replaced glowplugs, but this has nothing to do with the issue

-customer installed Autozone cps, I replaced with Ford CPS (it did have a cps code that went away after the Ford cps swap)

-checked FPR spring, as I've heard broken spring after warm up could cause excessive fuel pressure loss. That wasn't it.

-customer had previously installed new IDM with no change.

-customer changed the fuel pump too, no change.

-unplugging ICP sensor made an ever so slight change to idle, but still ran like poop after warmed up.

ICP IPR numbers look great
CCT passed perfect after injector swap
EOT sensor works
In fact all sensors available look fine via AutoEnginuity, even when running like crap and no codes.

Once it's reaches the running horrible stage, it even idles horrible. ICP/IRP look great at idle too.

If I shut the truck off and leave it set for a few, starts right up and idles/drives fine until it gets to full temp again.

Are there any other permissives that the engine NEEDS to see to run properly besides the obvious?

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hucorey

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Pretty good actually, even idles horrible, and it takes extremely little fuel to idle. If fuel pressure was bad, typically ICP numbers would show that too.

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hucorey

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I'm sort of leaning toward a pump issue myself, but the #'s are fine at idle. 480icp @ 9% when running like crap

Rev the engine when running like crap. ICP goes up to 1800ish @ 30%ish. I did not do a quick WOT at idle.

I also poured water slowly on the hpop while idling rough and no change.

I'm all sold out of our HPOP's too until I get more in next Friday.

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hucorey

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Idk where he got the IDM, but swapping them made no difference.

Injectors are new, Sam had a new reman stock AD's from FF.

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superpsd

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IPR is new. I assume ICP at idle is stable and not jumping around? Running rough when hot makes me suspect the Reman injectors like poppets bleeding off oil thru the upper seat once the oil gets hot. Might datalog ICP IPR.
 

hucorey

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Both sets of injectors did the same thing. I did data log ICP/IPR. numbers are fine.

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DEEZUZ

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Id look again at the fuel system. sounds like it is sucking air or lack of supply pressure.. maybe run it out of a bucket
 

hucorey

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All good. I'm going to drop the fuel tank.
If the wires were bad, perdels, and sensors would show.


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hucorey

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I'm going to say fuel pickup is getting plugged/restricted or fuel pump is on its way out.
Winner winner chicken dinner.



These are the internal screens right above the pick up. ******d them by doing the hutch mod.

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19232a5a51018a40bc7ea6e95d10897e.jpg


The center piece is a tiny 1/4" not to 1/4" barb. The ash tray was quite loose sucking air.

d3f44583f7718803ceb64ac1458c3f0e.jpg


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hucorey

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The owner of the truck told me that's what him and his buddy put in there. Not sure what the knife blade size slits are for???

He's a hot shot driver, so refueling I would hope is at any truck stop.

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