any diesel gurus?

DefinitiveDave

I do want to see skinny guys in speedos
Oct 24, 2013
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2002 7.3 Powerstroke @275K miles 4x4
we have been chasing this weird problem and need some sage advise

occasionally just shuts off while driving, will start right backup and drive fine after
intermittent but it will ALWAYS die if you back up and hit the brakes hard, in regular driving it sometimes goes weeks without dying and then dies 4 times in a day
this really sucks for a plow truck :(

Our regular mechanic is not a diesel guy, but believes he eliminated the fuel pump as a problem.

The local performance diesel shop says motor, electronics and wiring all good and that it "must be" the tranny

The Ford dealer says the diagnostic computer shows no code so the tranny must be good.

WTF???? any thoughts?
thanks
Dave
 

mdavlee

How the heck did this take so long?
Jan 10, 2012
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Low oil sensor? There's no high pressure fuel pump. Only a high pressure oil pump or HPOP for the injectors to fire. If it's starving for oil it will die. The low pressure oil pump could be weak.
 
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olyman

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would be nice,,if you had someones on board diagnostic computer,,to keep in there.. and reset it, each time you drive it,, to show the trouble code, when it hiccups..hiccups can be a sob to trace.....
 
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dieselfitter

Aspiring impressionist
Oct 12, 2013
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Hugo, MN
The transmission it the problem.
The torque converter has a clutch in it to lock up and eliminate slippage(for mileage and performance). There is cross leakage of oil within the transmission that is applying the torque converter clutch and stalling the engine. It is just like letting the clutch out to quickly on a manual transmission and stalling the engine. The fix it to rebuild the transmission(pay special attention to the pump, valve body and also check the trans case for warpage at the valve body where the center support bolts are. Always replace the converter when rebuilding the trans. This converter is sure to be smoked from being applied when it shouldn't be.
 
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DefinitiveDave

I do want to see skinny guys in speedos
Oct 24, 2013
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Low oil sensor? There's no high pressure fuel pump. Only a high pressure oil pump or HPOP for the injectors to fire. If it's starving for oil it will die. The low pressure oil pump could be weak.
Had an Hpop die before in one of the 7.3s, this feels different. The HPOP felt like it ran out of gas and would not restart. Mechanic rigged a fuel pressure sensor and an alert light to check if the fuel pressure dropped when it stalled.
My brother drove around for 2days with a bundle of wires and a gauge tape to the drivers side mirror:)

I appreciate all the suggestions
Dave
 
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DefinitiveDave

I do want to see skinny guys in speedos
Oct 24, 2013
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would be nice,,if you had someones on board diagnostic computer,,to keep in there.. and reset it, each time you drive it,, to show the trouble code, when it hiccups..hiccups can be a sob to trace.....
I forgot mention we have a generic ORC module and it detected no codes :(
DD
 

DefinitiveDave

I do want to see skinny guys in speedos
Oct 24, 2013
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Aftermarket chip by any chance?
Jody at DP Tuner does ours, and we took it out as soon as it started to no avail, tuner works fine in other 7.3s, even tried swapping ECMs.
Currently no tuner in this truck
Dave
 
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DefinitiveDave

I do want to see skinny guys in speedos
Oct 24, 2013
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The transmission it the problem.
The torque converter has a clutch in it to lock up and eliminate slippage(for mileage and performance). There is cross leakage of oil within the transmission that is applying the torque converter clutch and stalling the engine. It is just like letting the clutch out to quickly on a manual transmission and stalling the engine. The fix it to rebuild the transmission(pay special attention to the pump, valve body and also check the trans case for warpage at the valve body where the center support bolts are. Always replace the converter when rebuilding the trans. This converter is sure to be smoked from being applied when it shouldn't be.
a few more details my brother reminded me of.

initially the tranny wouldn't shift into reverse and was "grabby" and "jerky" on the way to the garage for repair. It got a billet torque converter u shorty thereafter the stalling began
it is a 2001 not a 2002 , sometimes you have to really crank it before it will restart
It sometimes stalls right after hitting a big pothole or several quick bumps

Sounds like tranny rebuild time???

Many thanks guys and especially Dieselfitter !!!!!
 

olyman

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Jan 7, 2014
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I forgot mention we have a generic ORC module and it detected no codes :(
DD
I like his trans suggestion.... and about the reader,,,,NO!!!! been there, done that!!! Ford one, Snap on one,,or another good brand, or youll be chasing your tail.....................
 
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RVALUE

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Jan 10, 2012
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I have a f250 2002 4x4 7.3 diesel. I've fixed everything. There is an o ring on the return hose in the filter housing. this can leak and drop the pressure. I put a gauge on my cap, mine wouldn't run at 55 psi. It would run at 70. The book says 55. Also, the intake fuel manifold in the tank can crack. drawing air. I put one of those hard to find o rings in my wallet, never had any more problems with the 0 ring. LOL

Don't go to the dealer for that o ring.
 
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trx250r180

The Junk Peddler
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one of my old tow trucks did this ,i replaced this and it was fixed

[video=youtube;wTsoRDZ2axo]https://www.youtube.com/watch?v=wTsoRDZ2axo[/video]
 
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jrepairsk70e

any name [cept shithead]
Jan 10, 2012
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Ulser County N.Y.
I have a 96 pwr strk with 180k on it ,,on its 3rd cps ,,symptoms start with studdering,flat throttle response ,,stalling @ low rpms ,,then intermittently shutting down while driving down the road but restarts after a couple minutes , I think eng temp affects it when it starts to get tired ,,,never stores any helpfull codes ,,change out the sensor and good to go for nother 50 k [I keep a new spare in the glove box ] knock on farwood this truck has always brought me home !!!:wave:
 
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mdavlee

How the heck did this take so long?
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I remember when those sensors were $200. Hard to keep a spare around when you drive a lot.
 
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dieselfitter

Aspiring impressionist
Oct 12, 2013
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Hugo, MN
a few more details my brother reminded me of.

initially the tranny wouldn't shift into reverse and was "grabby" and "jerky" on the way to the garage for repair. It got a billet torque converter u shorty thereafter the stalling began
it is a 2001 not a 2002 , sometimes you have to really crank it before it will restart
It sometimes stalls right after hitting a big pothole or several quick bumps

Sounds like tranny rebuild time???

Many thanks guys and especially Dieselfitter !!!!!
It sounds like possibly multiple issues between the hard starting and the stalling in reverse.
To help qualify it as a trans/torque converter issue, put the t-case in neutral and see if the stalling problem ceases.

It is somewhat normal for the stock trans to have a slightly delayed reverse engagement. Especially earlier pre 1995? transmissions. There are three clutches applied in reverse (most transmission only need to apply 2 for reverse) combined with the low idle(equals low oil pump volume) it creates a delay. Around 1995, the oil pump was changed to increase volume. That helped.
When I used to rebuild them, I would tighten up clutch clearances to minimize the delayed engagement. I would also put increase the quantity of clutches within the drums.
 
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trx250r180

The Junk Peddler
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think i paid around 70 bucks for a A/M one ,,still cheaper than towing this freight train anywhere [ crewcab/8ft box ,,and quite often towin sumthin]:wave:

I got one for about 30 bucks from Napa ,I have a commercial account though ,not sure if that drops the price much or not ?
 
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mdavlee

How the heck did this take so long?
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They're cheap now. I just remembered when all you could buy was Motorcraft
 
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DefinitiveDave

I do want to see skinny guys in speedos
Oct 24, 2013
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It sounds like possibly multiple issues between the hard starting and the stalling in reverse.
To help qualify it as a trans/torque converter issue, put the t-case in neutral and see if the stalling problem ceases.

It is somewhat normal for the stock trans to have a slightly delayed reverse engagement. Especially earlier pre 1995? transmissions. There are three clutches applied in reverse (most transmission only need to apply 2 for reverse) combined with the low idle(equals low oil pump volume) it creates a delay. Around 1995, the oil pump was changed to increase volume. That helped.
When I used to rebuild them, I would tighten up clutch clearances to minimize the delayed engagement. I would also put increase the quantity of clutches within the drums.



OK doug did one more test to try to narrow this down.

Reverse up to speed, shift to neutral, brake hard = stall
tried multiple times in empty parking lot with longer intervals between neutral and braking, always stalled

Dave
 

dieselfitter

Aspiring impressionist
Oct 12, 2013
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Hugo, MN
OK doug did one more test to try to narrow this down.

Reverse up to speed, shift to neutral, brake hard = stall
tried multiple times in empty parking lot with longer intervals between neutral and braking, always stalled

Dave
That doesn't sound like the a transmission issue. When it is the transmission/TC, you will feel the drive line tense up. It is just like stalling the engine with the clutch on a manual transmission.
Maybe a electric circuit opening. With the engine running, vehicle stopped, have someone climb around underneath the hood and truck and wiggle/tug on wires and harness.
 
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