[tuckersheets]

I have had my 94.5 7.3 to almost every mechanic I know, they have all put new parts on, none have solved the problem. It will run great all day, as long as you leave it running. If you shut it off it's like it loses its prime and it will crank all day and never fire. If you let it sit for an hour or so it cranks a lot and hesitantly starts. After sitting all night it pops right off. Anyone have any thoughts?

 

[Bugman]

I doubt that it is a fuel issue. The first thing I would do is to drive it around until it is up to temperature and then shut it off. Get some ice water and poor it onto the IPR and then see if it will start.

When hot the IPR O rings will cause problems like your hot no start. Other than that you may have to look at the injector O rings.

You can replace just the IPR O rings if it does start up.

The last thing that I think that I would do is to find a competent mechanic that know something about a diesel engine.

 

[cjfisher]

Welcome to PSN!
What new parts have been installed? How many miles on the truck? Data can only help... Has the in-cab OBD port been enabled (at least I think the 94.5's came with an in-cab port)? I've posted this blurb in more than a few places: "I would recommend that you first invest in FORScan (forscan.org) and a suitable adapter. I have an OBDLink EX usb adapter (should you wish to use a computer to collect data), or take a look at either a BAFX or OBDLink unit. Both BAFX/OBDLink have a bluetooth/Wifi units (there are a few folks around here that recommend them) that will would work with a smart phone (Run of the mill box store scanners and even a great number of the higher end scanners can't touch these trucks as Ford used the "heavy duty diesel" protocol for communication). Once you are setup I would capture data.. At minimum I would save RPM (really this is CPS), ICP, IPR, MAP, EOT and IVS (at least I think that is the PID for the go petal). FORScan will allow you to save the data as a .csv file which you can import into excel. The information you get from the truck will help identify what your problem really is without just "throwing parts" at the truck."
Bugmon posted a couple of possibilities - another is that the HPOP is getting weak. Cold oil is more viscous when cold. Hot oil leaks through worn parts much easier. The HPOP can be tested by dead-heading it. You will need a blanking tool - RiffRaff Diesel sells a good one - and a 5000 psi hydraulic gauge. I have also read of internal leaks in injectors that can cause similar symptoms.

Cj

 

[tuckersheets]

I doubt that it is a fuel issue. The first thing I would do is to drive it around until it is up to temperature and then shut it off. Get some ice water and poor it onto the IPR and then see if it will start.

When hot the IPR O rings will cause problems like your hot no start. Other than that you may have to look at the injector O rings.

You can replace just the IPR O rings if it does start up.

The last thing that I think that I would do is to find a competent mechanic that know something about a diesel engine.

I have had my 94.5 7.3 to almost every mechanic I know, they have all put new parts on, none have solved the problem. It will run great all day, as long as you leave it running. If you shut it off it's like it loses its prime and it will crank all day and never fire. If you let it sit for an hour or so it cranks a lot and hesitantly starts. After sitting all night it pops right off. Anyone have any thoughts?

edit, additional info. 223,000 miles. I can’t give you all the new part without digging up 6 months of receipts. There is fuel pooling in the valley, a small puddle under it when sitting running, and smell of fuel through the vents going down the road. Sometimes it also dies turning sharp left. I change fluids and filters, can replace alternators, power steering pump, stuff like that. Anything beyond that is out of my mechanicing abilities. I won’t be buying any Specialty tools for a job I cannot perform. My current mechanic has been very good but this one is apparently stumping him.

 

[Bugman]

The fuel pooling is one of 3 things. The lift pump, filter housing, or the hoses from the pump to the filter housing.

Just a WAG but on the dieing on turns I'd disconnect the fuel heater in the filter housing. I've read where if it is loose it may contact the side of the filter housing without shorting out and killing the engine.

Even iyou have a good relationship with your mechanic I would still find one who is familiar with diesel engines. It sounds like he is just shotgunnibg parts at it with zero test performed to see if what he replacing is even bad. The fuel leak is a good example of this. It is a easy diagnosis of where the problem lies.

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[tuckersheets]

The fuel pooling is one of 3 things. The lift pump, filter housing, or the hoses from the pump to the filter housing.

Just a WAG but on the dieing on turns I'd disconnect the fuel heater in the filter housing. I've read where if it is loose it may contact the side of the filter housing without shorting out and killing the engine.

Even iyou have a good relationship with your mechanic I would still find one who is familiar with diesel engines. It sounds like he is just shotgunnibg parts at it with zero test performed to see if what he replacing is even bad. The fuel leak is a good example of this. It is a easy diagnosis of where the problem lies.

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Fuel heater was disconnected long ago. There isn’t a lot of choices out here, my guy worked for ford for 20 years before starting his own shop. So he’s probably the best powerstroke guy around.

 

[Bugman]

When it dies do the warning lights such as the WTS and CEL lights come on? Or does it just die?

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[tuckersheets]

When it dies do the warning lights such as the WTS and CEL lights come on? Or does it just die?

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No lights

 

[Bugman]

Do the cold ice water trick on the ICP when it won't start and see what it does

The fuel leaks are simple. Clean up as much of the fuel as you can then sprinkle baby powder down between the pump and filter housing and check it after it has been run for a bit. The fuel will slowly migrate into the powder leading you to where the problem is.

The dieing sounds like a wiring problem or a loose connector that when you turn some torque is placed on the wire or connector killing the engine. These can be a bear of a problem to find

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[Bugman]

One other thing.

These engines have so many sensors and inputs into the PCM that a way to read live data when a problem is happening such as your hot no start is almost required to diagnose the problem.

As was mentioned FORScan Lite will run on a smart phone and the ELM 327 adapter can be bought for around $30

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[1970something]

dry off the fuel filter housing real good and then fire it up for a minute or so. then check for wet on the filter housing. my bet is you will find the filter housing is leaking. whether the drain, cracked bowl, or bad top. but that is where i would start looking.

 

[tuckersheets]

I doubt that it is a fuel issue. The first thing I would do is to drive it around until it is up to temperature and then shut it off. Get some ice water and poor it onto the IPR and then see if it will start.

When hot the IPR O rings will cause problems like your hot no start. Other than that you may have to look at the injector O rings.

You can replace just the IPR O rings if it does start up.

The last thing that I think that I would do is to find a competent mechanic that know something about a diesel engine.

If it was the IPR, it shouldn't start at all until it cools correct?

 

[Bugman]

If you poor cold water on the IPR and it starts then I would say the IPR O rings if it still doesn't start then I'd look at the injecto O rings.

The reason it might start when it has cooled down is the O rings may reseal keeping the oil where it is suppose to be instead of flowing past them

This is where your mechanic should have a scanner that will read live data. It would take a lot of guesswork out of the equation

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[tuckersheets]

If you poor cold water on the IPR and it starts then I would say the IPR O rings if it still doesn't start then I'd look at the injecto O rings.

The reason it might start when it has cooled down is the O rings may reseal keeping the oil where it is suppose to be instead of flowing past them

This is where your mechanic should have a scanner that will read live data. It would take a lot of guesswork out of the equation

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i just wonder because after it dies, a little squirt of starting fluid and it fires back up. Seems like if the IPR being hot was the issue it still shouldn't start?

 

[Bugman]

Starting fluid bypasses everything except for the intake valve and cylinders it won't affect a thing with the high pressure oil system

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[Jim P]

I have had my 94.5 7.3 to almost every mechanic I know, they have all put new parts on, none have solved the problem. It will run great all day, as long as you leave it running. If you shut it off it's like it loses its prime and it will crank all day and never fire. If you let it sit for an hour or so it cranks a lot and hesitantly starts. After sitting all night it pops right off. Anyone have any thoughts?

I have a 97 7.3 have at times experienced a total shut down on the road or when releasing the parking brake. Talked to a mech who said it may be related to a bad connection to the chip/computer hidden in the wall between the brake release pedal and the body. Apparently over time the elecrical contacts can get loose and break contact. I do have a mini Banks mod with chip but the mech I talked to said he has seen it happen in non-modified trucks as well. Have no idea if it relates to you but that’s what have learned from experience. Frankly, your problem sounds more related to the uplift fuel pump. I changed that and immediately the truck started and runs better, however I still anticipate occasional shut down related to electrics. Mech left me with the thought that the pump and chip/electronic signals can be related.
I live in damp climate which exacerbates the possibility of poor electrical connections. Dunno, but that might help with your diagnosis..Good luck on the hunt.

 

[jvh]

I have a 2002 F-250 with a 7.3. Last year when we went camping, I drove my it all day on a trout fishing trip in the mountains of North Carolina. About 4:00 pm I pulled into a parking lot and truck shut down like I turned off the key. It would not even fire and it was sitting on a slight incline. Replaced the crankshaft sensor and checked all of the fuses, still nothing. Had it on a rollback for about 125 miles and when it came off, it fired right up. The mechanic that I used replaced the IPR. Years earlier he worked on a E-250 van and it would run, then when he came to a stop light it would cut off. The inside of the IPR would slide forwards and that would cause it to cut off. He had also replaced my high pressure oil pump about a year before, but used my old IPR.

 

[Jim P]

Good to know. I’m still on the hunt even though it seems I did find a short term fix. Runs fine with new fuel pump, however I am likely not out of the woods for potential shutdown surprises. There is definitely more to this problem and is beyond my 'pay grade’..anyway, thanks for the added info. Will keep this in mind.
BTW, in your opinion do you think installing an electric fuel pump would help cure the surprise shutdown issue?

 

[Patrick Feeley]

IMO, if a good mechanical fuel pump didn't cure the problem, a e-fuel system would not either. Cheers!

 

[Jim P]

Thank you. So far I can live with the problem but will eventually have to chase it down.