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Discussion Starter #1 (Edited)
Ive been looking at my father in laws truck and not sure whats going on . Cold starts ok but drive it a few miles let it set for a few min on restart it idles romp, romp ,romp rev it up it clears that up but still has a little rough idle. The truck has new heads , valves and glowplugs .it has 148000 . When he bought it they did this the # 8 valve was very thin and that injector was also bad.It has some blowby that seems to be getting worse. I checked the fuel pressure and its bouncing between 5 and 20 * so replacing fuel pump.My ? is could the low fuel pressure be whats up with all of these problems? I read somewhere that low fuel pressure retards the timing and causes late injections in the stroke. Kind of sounds like a reach but hoping thats some of the blowby. The idle is lower than it should be too , around 700. Any ideas would greatly be:confused: appreciated
 

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Fuel pressure is way low, at least 40-60 PSI I believe is the spec, 1997 pretty sure fuel pump is in the tank also, that sucks not that hard just more time consuming. To answer your question are all these related could be, no way to know for sure until you fix what you know is wrong then see what happens. Have you pulled the codes yet?
 

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Discussion Starter #6
I have pulled codes with his edge evo but its not showing any . The fuel pump on it is mechanical its an obs .
 

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There aint a 7.3 powerstroke with a fuel pump in the tank. 94-97 is mechanical on top of the engine, 99-03 is electric on the frame rail under the driver’s seat. Fuel pressure is way low and that can cause runability problems and injector damage. One thing that can cause hard start when warm is IPR o-rings. The worn valves and blowby sound like dusting. Same thing happened to mine because of the crappy factory air intake and a sloppy previous owner. Had to have all the valves replaced and rebuild the engine and replace the injectors, cost me $4000.
 

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Discussion Starter #9
Thats what I'm hoping has'nt happened , but thats what i was thinking too . When they changed the valve and injector they looked at the cylinder and said they thought he would be ok. But they put it back together and didnt check compression . When they saw that valve they thought that was were the loss in compression was , it had 375 on #8 cylinder 475 on the rest.
 

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Wow, 375 and 475. Thats pretty darn good, if mine had been over 300 I would have not rebuilt it. 475 seems too high, considering that and that they didn't recheck it after "fixing" it I would have to question their competence. Don't forget that some blowby is normal. Mine was chugging out the ccv mod and the dipstick tube pretty hard.
 

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Discussion Starter #11
Yeah I looked at that again and it was 325 and 425 on the rest , I dont know where i got those #'s from. Its blowing pretty bad from the ccv and the oil fill hole. I havent checked the dipstick but i would say its doing it there too.
 

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I wouldn't worry as much about the 325 if it weren’t for the imbalance of it with the others being 425. 425 is pretty darn good, may be time for a leak down test to see what’s wrong with 8. One cylinder should not get dusted by itself, must be something else wrong. I also think there is a way to do a blow by pressure teat on the motor.
 
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