95 7.3 start up problems
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95 7.3 start up problems
Bought my first diesel truck over the summer. Its a 95 F-super duty with 203,000 on it. Ran good for a couple months then developed a start up issue.Here are the details-Only happens when truck is fully warmed up, cold start OK. Cranks over but misses and vibrates badly(shakes whole truck) If does manage to start it will stall in seconds. Immediately try again and she starts right up.This is an intermittent problem that is increasing in its frequency.Only other issue that could be related is a erratic or stumbling idle when coming off of throttle at a stop sign or red light. Never stalls but comes close then stabilizes. This also is intermittent. This is my first post but have read some advice before joining today.Thanks
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Joined: Nov 2006
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From: Herndon KY
Welcome to FTE. Check the CPS Cam position sensor, they can cause problems when warm. and should be less the 30 bucks to fix, if that is not the problem then you can use your old one as a spare.
Other than that it Sounds like you have an IPR (Injector Pressure Regulator) issue, most likely O rings. On top of your engine, just to the left and below the A/C pump is the HPOP (high Pressure oil pump) on the back side of the hpop closer to the cab, you will see a brass cylinder. This is an electro magnet, there is a brass "cheap nut" screwed on behind the cylinder (it has to be nonferrous) make sure that is tight, dont crank to hard cause won't take much. If the CPS and Cheap nut don't pan out you need to replace your O rings on the IPR, that is the contraption that is actually screwed in to the HPOP.
The operating theory is this the electro magnet slide the pilot valve in and out inside the hpop rediricting oil changing pressure and volume, when the oil is warm, it is more fluid, so deteriourating o rings would be more of an issue, causing erratic hpop pressures and volume. The high pressure oil is what causes the injectors to fire diesel into the motor, so erratic oil pressure and volume = erratic idle. Same with cheap nut electro magnet moving around means the Pilot valve is not moving, same issue as above
Other than that it Sounds like you have an IPR (Injector Pressure Regulator) issue, most likely O rings. On top of your engine, just to the left and below the A/C pump is the HPOP (high Pressure oil pump) on the back side of the hpop closer to the cab, you will see a brass cylinder. This is an electro magnet, there is a brass "cheap nut" screwed on behind the cylinder (it has to be nonferrous) make sure that is tight, dont crank to hard cause won't take much. If the CPS and Cheap nut don't pan out you need to replace your O rings on the IPR, that is the contraption that is actually screwed in to the HPOP.
The operating theory is this the electro magnet slide the pilot valve in and out inside the hpop rediricting oil changing pressure and volume, when the oil is warm, it is more fluid, so deteriourating o rings would be more of an issue, causing erratic hpop pressures and volume. The high pressure oil is what causes the injectors to fire diesel into the motor, so erratic oil pressure and volume = erratic idle. Same with cheap nut electro magnet moving around means the Pilot valve is not moving, same issue as above
Post Fiend
Joined: Oct 2003
Posts: 5,903
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From: MICHIGAN
Starts up OK cold......hard to start hot= IPR o rings
Look here:
http://cw-diesel.com/LuxSite/IPRInfo.htm
Get a new CPS anyway and put it in the glove box. It will save you from walking. They go bad with no warning.
Look here:
http://cw-diesel.com/LuxSite/IPRInfo.htm
Get a new CPS anyway and put it in the glove box. It will save you from walking. They go bad with no warning.
Last edited by Cuda_jim; Oct 22, 2007 at 07:27 AM.
Senior User
Joined: Apr 2004
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From: Taylorsville, KY
Welcome to FTE. You should be able to get the cps at NAPA for that price. the part number is CSS512. most of the stores should keep that part in stock but if the one near you doesnt the can get it pretty easily.
Franklin
Franklin
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Joined: Aug 2006
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Heres another thing to check
This is from Swamps:
Though it could be the IPR, I don't think it's likely in this case.
I'm betting that you have some injector issues...specifically surrounding the poppet valve on one (or more) injectors.
The poppet valve is the one single area of a PSD injector that just flat out wears. It's similar to a valve in a cylinder head that beats itself into it's valveseat.
As the poppet valve opens and closes (with each injection), it meters the high pressure oil flow in/out of the inj.
With each opening and closing, the seat is being hammered by the valve...causing it (over millions of cycles) to seat lower and lower into the injector...until clearance under the armature is lost.
Once the armature bottoms out on the inj body, the valve cannot "reach" the seat to seal high pressure oil from leaking out of the injector.
The reason that the truck runs when cold, and dies (and won't restart until it has cooled significantly) is that cold oil is thick...and can bridge the gap created by a poor valve & seat seal.
once the oil is warm, it thins out, and can now leak around that valve creating a tremendous amount of "spillage" that the oil pump can not now keep up with...once the amount of the leak exceeds the capacity of the pump...pressure falls, and the injectors simply cannot fire without (approx) 450psi of high pressure oil...so the truck dies.
you can physically measure this yourself.
Pull both valvecovers, and start the truck...it won't be horribly messy, just a little oil splash around the valvetrain.
As the truck (oil) heats up and dies, have someone crank on the starter attempting to restart the truck.
You should be able to look at each injector, and find one that it puking oil out from around the (just above) the hold down clamp.
You may need to mop up any oil that settles down in the low spot of the head to help you see which injector is actually puking...
once you've isolated which inj(s) are puking, pull the solenoid (4 # torx 15 screws), remove the harness to that inj, remove the little aluminum spacer plate...
what you are now looking at is the armature plate...the little ~1"x1" square plate, with the goofy screw (poppet screw) going through it's center.
On a brand new injector, there should typically be .003"-.004" (three to four thousanths of an inch) gap under that armature (measured with a feeler gauge)...
My bet is that your injectors have enough poppet seat wear that they have less than .0015 (less than one and one half thou of an inch) gap...practically zero.
if you can't get a .0015" feeler under the armature plate, then that injector is a problem, and it is a good indication that the others within that set need some machining to bring them back into spec. so that they will operate correctly.
This is from Swamps:
Though it could be the IPR, I don't think it's likely in this case.
I'm betting that you have some injector issues...specifically surrounding the poppet valve on one (or more) injectors.
The poppet valve is the one single area of a PSD injector that just flat out wears. It's similar to a valve in a cylinder head that beats itself into it's valveseat.
As the poppet valve opens and closes (with each injection), it meters the high pressure oil flow in/out of the inj.
With each opening and closing, the seat is being hammered by the valve...causing it (over millions of cycles) to seat lower and lower into the injector...until clearance under the armature is lost.
Once the armature bottoms out on the inj body, the valve cannot "reach" the seat to seal high pressure oil from leaking out of the injector.
The reason that the truck runs when cold, and dies (and won't restart until it has cooled significantly) is that cold oil is thick...and can bridge the gap created by a poor valve & seat seal.
once the oil is warm, it thins out, and can now leak around that valve creating a tremendous amount of "spillage" that the oil pump can not now keep up with...once the amount of the leak exceeds the capacity of the pump...pressure falls, and the injectors simply cannot fire without (approx) 450psi of high pressure oil...so the truck dies.
you can physically measure this yourself.
Pull both valvecovers, and start the truck...it won't be horribly messy, just a little oil splash around the valvetrain.
As the truck (oil) heats up and dies, have someone crank on the starter attempting to restart the truck.
You should be able to look at each injector, and find one that it puking oil out from around the (just above) the hold down clamp.
You may need to mop up any oil that settles down in the low spot of the head to help you see which injector is actually puking...
once you've isolated which inj(s) are puking, pull the solenoid (4 # torx 15 screws), remove the harness to that inj, remove the little aluminum spacer plate...
what you are now looking at is the armature plate...the little ~1"x1" square plate, with the goofy screw (poppet screw) going through it's center.
On a brand new injector, there should typically be .003"-.004" (three to four thousanths of an inch) gap under that armature (measured with a feeler gauge)...
My bet is that your injectors have enough poppet seat wear that they have less than .0015 (less than one and one half thou of an inch) gap...practically zero.
if you can't get a .0015" feeler under the armature plate, then that injector is a problem, and it is a good indication that the others within that set need some machining to bring them back into spec. so that they will operate correctly.
Freshman User
Joined: Oct 2007
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I think the info from the previous menbers is correct however just wanted to add one other tid bit. I have a 96 7.3l two fitty with a five speed and developed over time a rather violent shaking and chattering condition. Turns out my dual mass flywheel ( ford junk ) was about to self destruct. Not sure if you have an auto or not, it is nice to hear a otherwise good running truck with high mileage. I only have 85k on mine. Just breaking it in. Good Luck.
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Joined: Aug 2006
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Originally Posted by new2dsls
Bought my first diesel truck over the summer. Its a 95 F-super duty with 203,000 on it. Ran good for a couple months then developed a start up issue.Here are the details-Only happens when truck is fully warmed up, cold start OK. Cranks over but misses and vibrates badly(shakes whole truck) If does manage to start it will stall in seconds. Immediately try again and she starts right up.This is an intermittent problem that is increasing in its frequency.Only other issue that could be related is a erratic or stumbling idle when coming off of throttle at a stop sign or red light. Never stalls but comes close then stabilizes. This also is intermittent. This is my first post but have read some advice before joining today.Thanks
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Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
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From: Southwest Georgia
new2dsls, Ford dealers have the new CPS (part# F7TZ-12K073-B) for around $30.
Changing the IPR o-rings is not hard. First you need something to suck the oil out of the HPOP (a mighty vac, brake bleeder vac, large stock syringe & tube). Once the oil is out, unplug the IPR electrical connection, remove the Timmerman nut, unscrew the IPR from the back of the HPOP ( have paper towels under the IPR in the valley to catch the oil that leaks out). Remove the old o-rings, install new o-rings.
Installation is in reverse order. Refill the HPOP and your done. Taking your time, about a 2 hour job.
From http://www.thedwilsons.com/powerstro...t_Numbers.html site: IPR O-Ring Kit (for when IPR valve replacement is not required) (Ford) F6TZ-9C977-AN (F6TZ-9C977-AA?) (International) 1825806C92 (1825806C91?)
Changing the IPR o-rings is not hard. First you need something to suck the oil out of the HPOP (a mighty vac, brake bleeder vac, large stock syringe & tube). Once the oil is out, unplug the IPR electrical connection, remove the Timmerman nut, unscrew the IPR from the back of the HPOP ( have paper towels under the IPR in the valley to catch the oil that leaks out). Remove the old o-rings, install new o-rings.
Installation is in reverse order. Refill the HPOP and your done. Taking your time, about a 2 hour job.
From http://www.thedwilsons.com/powerstro...t_Numbers.html site: IPR O-Ring Kit (for when IPR valve replacement is not required) (Ford) F6TZ-9C977-AN (F6TZ-9C977-AA?) (International) 1825806C92 (1825806C91?)
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My truck is scheduled for diagnostics monday.What bigblue15 said about the dual mass fly wheel concerns me.The mechanic I am dealing with said when those blow up the transmission (bell housing) goes with it to the tune of a nice repair bill. I am just starting to learn about diesel engines but I cant understand how a problem with fuel delivery to all injectors (IPR issue) would cause such a severe vibrating shaking episode.I could see cranking and no fire but what I have is hard to describe unless you hear it. I will pull valve covers before monday to see if maybe there is an issue with an isolated injector. Anyone else experienced the symptoms of a failing dual mass flywheel? There is always the possibility of a couple different problems here I guess. Thanks for the advice, great info here.
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
Likes: 1
From: Southwest Georgia
Usually but not always, a failing DMF will start with a loud "CLUNK" and shake when you turn off your truck. Then later on as it gets worse it will start a vibration at certain RPMs (usually goes away if you step on the clutch or press/let off on the accelarator). Then as it gets real bad, it will not pull under load at certain RPMs. And sometimes the springs will turn loose get shot out of the DMF. What usually gets the bell housing is the severe vibrations and letting it go on for a long time. Hope this helps some.
I have never seen a failing DMF cause a starting isssue. Also if you need to replace your DMF, DO NOT PUT ANOTHER DMF IN IT!!!!!!! Go with a SMF like LUK, South Bend, Valair (spl) (RubberDuck has one). They will hold more power and you'll like it better, also cheaper in the long run.
I have never seen a failing DMF cause a starting isssue. Also if you need to replace your DMF, DO NOT PUT ANOTHER DMF IN IT!!!!!!! Go with a SMF like LUK, South Bend, Valair (spl) (RubberDuck has one). They will hold more power and you'll like it better, also cheaper in the long run.
Last edited by plowhand; Oct 24, 2007 at 07:49 AM. Reason: addition
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