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Sunday afternoon riddle: 7.3 randomly dies.

Maverick

Maverick

old-school
Location
Anywhere, thanks to my geeky droid
My '02 7.3 X has randomly died a few times recently. When it dies, it is typically after coming to a stop or coasting. When it does, it acts like I turned off the key, just dead. It cranks no problem, just doesn't start back up (usually starts immediately). When running, no hesitation, plenty of power.


  1. Died once a year ago on the way home from a trip from Zion Narrows, pulling into a gas station in Scipio, tried swapping the fuel filter, started right up and drove home.
  2. Died coming down from our cabin last winter, coming to a stop, tried the fuel filter, no dice. Swapped in a CPS (3rd one) started up and drove home.
  3. Happened towing back from Rubicon in Carson City 2 weeks ago, pulling in to motel. Started back up after a minute. Swapped in CPS just to be safe the next morning.
  4. Drove for 1 hour or so, died again in Winnemucca, idling while filling up. Started up but died a block away. Since it had a new CPS, I tried the fuel filter again (fuel filter wasn't that old). Started up and drove home (400 miles towing heavy)
  5. Happened again yesterday. Started back up, then died. Only been driven a couple times since the Rubicon trip. Went online, checked relays, checked for loose things under the hood, etc. Started up then died. Finally, swapped in a new fuel filter and it started right up and continued running.
  6. It doesn't seem to matter what position the DPTuner chip is in.
  7. Pulled the codes, nothing but overpressured injectors and low turbo boost, which is a typical code I get from time to time from the chip when I hit warp drive.

Any ideas? Do I just buy a case of fuel filters?

Could it be a clogged fuel pickup that unclogs after it sits and/or pressure is released? Something else that is really expensive?
Thoughts?
 
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clfrnacwby

clfrnacwby

Recovery Addict
Location
NV
Have you replaced the IPR (Injection Pressure Regulator)? That seems to be a common issue with the 7.3.
 
Maverick

Maverick

old-school
Location
Anywhere, thanks to my geeky droid
Wouldn't it throw a code? I don't know much about the IPR. Is its failure consistent with the symptoms? What are the symptoms of a failing or failed IPR? Does it go all at once, or fail intermittently for a while?

It just seems weird to me that it's all or nothing, which seems electrical/electronic, consistent with a part like the IPR, but (seemingly) fixed with the fuel filter swap? Is there something that swapping the fuel filter does that masks or hides the problem of the IPR?

I wondered if just sitting for a long amount of time did it, but I tried immediately before the fuel filter swap, and immediately after, it worked. Swapping fuel filter took about 2 minutes. But would releasing the pressure (removing the cap) help anything? I mean, is it the fuel filter itself, or is it the process or removing and replacing the filter?
 
flexyfool

flexyfool

GDW
Location
Boise, Idaho
The symptoms sound exactly like my '96 7.3L. An International service shop replaced the CPS, and it never went bad again. I don't know if it matters, but the part was a true International part listed for their light-duty truck line -- not Ford, not aftermarket. I also vaguely remember a Ford forum posting that talked about needing to shim or trim to get it at the correct distance from the crank and ensuring that it sat squarely. I did not replace the part, but the posting implies there is some kind of gasket or shim pack to deal with.
 
Kevin B.

Kevin B.

Not often wrong. Never quite right.
Moderator
Location
Stinkwater
Maverick said:
I wondered if just sitting for a long amount of time did it, but I tried immediately before the fuel filter swap, and immediately after, it worked. Swapping fuel filter took about 2 minutes. But would releasing the pressure (removing the cap) help anything? I mean, is it the fuel filter itself, or is it the process or removing and replacing the filter?
Click to expand...

Could try just cracking the fuel lines and then putting them back on the same filter?
 
clfrnacwby

clfrnacwby

Recovery Addict
Location
NV
ChestonScout

ChestonScout

opinions are like Jeeps..
Location
Clinton, Ut
Is it overdue for a oil change? oil low?


Its embarrassing but this happened in my 02 7.3 years ago. Sometimes randomly die, hard to start back up. Thought the worst but changed the oil and it ran perfect again. It was about 3000 miles overdue. It was in 08 when I was all but unemployed.
 
Badger

Badger

I am the Brute squad
Location
South Salt Lake
They will will die like that if they get low on oil. I know mine was doing it, when you checked the dip stick it showed a little low but not off the stick. It took a lot more then just a quart to bring it all the way back up. After then it stopped stalling and having the issues that you are describing.
 
1adam12

1adam12

THE BEAST
Location
MAGNA
The cps was recalled and will cause this. That would be my first guess, do you have an edge chip with the moniter?
 
idahoyj

idahoyj

Well-Known Member
Location
Twin Falls Idaho
My dads did this too.
Hes no diesel mechanic so he had it towed to the dealership, just to find out that the oil was low.
I think the engine oil runs the injector pump?
 
L

littlyota

Active Member
Location
Roy, Ut
Also throw a CPS in it. They are now about $24 or $28 at the dealer. The are known to fail. I carry a spare in my glove box.

It is about a 30 min job the first time, takes about 10 min once you have done it..

Depending on what you are reading codes with, you may not be getting all the codes. It takes special software or an expensive scanner to get the code from the individual modules. I have the software depending on where you live.

Your symptoms sound like CPS.
 
SLC97SR5

SLC97SR5

IDIesel
Location
Davis County
The above posts are all good advice and very common items on the 7.3L.

The HPOP requires a steady supply of fresh oil to fire the injectors. They do not like to run low or have thinned out, overdue oil.

I would replace the IPR and keep an eye on the thin tin nut that mounts it. It sounds like you have a handle on the CPS.

When you are draining the water seperator are you getting any junk out of it? Little black bits indicate failing O-rings inside the filter housing.
 
Maverick

Maverick

old-school
Location
Anywhere, thanks to my geeky droid
Thank you everyone for your replies and ideas!

Badger said:
They will will die like that if they get low on oil. I know mine was doing it, when you checked the dip stick it showed a little low but not off the stick. It took a lot more then just a quart to bring it all the way back up. After then it stopped stalling and having the issues that you are describing.
Click to expand...

It seems to have enough oil, I checked it before and after the Rubicon trip, no change even though it worked its butt off. It's got 5000 miles on it though. Getting changed on Thurs, it's due.

1adam12 said:
The cps was recalled and will cause this. That would be my first guess, do you have an edge chip with the moniter?
Click to expand...

It has a 5 position DPTuner. No monitor, just gauges.

ChestonScout said:
I would change the oil before you spend anymore money. It needs done anyway.
Click to expand...

Sounds like good advice. My only hesitation is that I'm hauling a 26' trailer full of stuff for Pioneer Trek in 10 days and this issue needs to be resolved by then.

littlyota said:
Also throw a CPS in it. They are now about $24 or $28 at the dealer. The are known to fail. I carry a spare in my glove box.

It is about a 30 min job the first time, takes about 10 min once you have done it..

Depending on what you are reading codes with, you may not be getting all the codes. It takes special software or an expensive scanner to get the code from the individual modules. I have the software depending on where you live.

Your symptoms sound like CPS.
Click to expand...

I'm running a brand new spare now...and thinking the one I replaced is fine, which is the one I swapped in that night at the cabin, which replaced the one that F*rd replaced on the recall in '07 or '08. The one they replaced was one that I had installed back in '06. I will buy another new spare. I live in Draper. Are you nearby?

SLC97SR5 said:
The above posts are all good advice and very common items on the 7.3L.

The HPOP requires a steady supply of fresh oil to fire the injectors. They do not like to run low or have thinned out, overdue oil.

I would replace the IPR and keep an eye on the thin tin nut that mounts it. It sounds like you have a handle on the CPS.

When you are draining the water separator are you getting any junk out of it? Little black bits indicate failing O-rings inside the filter housing.
Click to expand...

I didn't notice any junk, gunk or anything else...but I wasn't really looking closely. Oil changes have been pretty regular between 3500-4000 miles (by the time I notice and can get it in). I knew I was long on this one and was nervous about the pull. I wonder now if the other occurrences were oil related. I didn't notice the oil being any lower...it's in the operating range. I may order an IPR and keep it with my spare fuel filter and CPS. Do they come with the tin nut and O-rings? I see a kit at NAPA.

Any idea why changing the fuel filter (or relieving the pressure in the fuel bowl) would (temporarily) resolve the issue?
 
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1adam12

1adam12

THE BEAST
Location
MAGNA
Ive been told by a friend of mine who is a ford diesel mechanic not to run any kind of synthetic. He says it is really bad for the injectors.
 
SLC97SR5

SLC97SR5

IDIesel
Location
Davis County
I know the Motorcraft IPR's come ready to install. Not sure about the parts store units.

You might also pull the plug off the back of the ICP and make sure it is clean and dry. If it is full of oil that is a sign on a failing ICP.
 
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