93 6.5 turbo trouble

[lineman]

OK guys, I can't find the problem with my truck.This may be long! I have 172k on my 1993 3/4 ton (c6p) 4wd 6.5 turbo 5-speed. I have only changed out the alt. twice, water pump once, a fuel shutoff switch and two lift pumps in 168k.I love my daily driver ( about 120 miles a day ) @ 18mpg with 4:10 gears. At 169k the injector pump was getting weak, so I changed it out myself, along with new injectors and glow plugs. It took a whole weekend, and a few beers but I was proud of myself! I did forget about changing out the clutch at 120k. That took two weekends and some whisky ! But to my new problem. After putting the glow plugs ,injectors and a rebuilt inj. pump from a Stanadyne Dealer ( not my original pump )on my truck it ran great that day. The next morning on cold startup, it started right away but reved to 3k instantly.I jumped from the truck and unpluged the fast idle connector. This dropped it to 850 rpm.I have tried this again with the same results so I have left it off.The next 3k miles have been heaven, no problems until the last 600 miles.It started while upshifting, engine cold or hot.Between 2200 and 3000 rpm the truck would surge 300rpm or so ( that I could't feel on the throttle @ my feet. )I'd shift and then the truck would feel like it was lopeing 3 or 400 rpm until I clutched it. When I clutched it,it would settle back down.But it was a bucking ride until I clutched it.This happened once or twice a day. Now it happens 5 or 6 times a day.Then today on the freeway at about 2300rpm in 5th gear it felt like someone threw a switch on for about 5 seconds that gave me 50 hp then went away, smoothly.This happened twice coming home.I don't know where to start looking for the problem. Is it the turbo ( which sounds like it is working ), the turbo actuator or the inj. pump?I don't want to r&r the pump if it isn't needed, but if it's the pump,I need to do it before the warranty goes out.Does the inj. pump have anything electric in it that could do this even though I have the fast idle unhooked.Remember this is a mech. inj. pump.Someone tell me what is wrong so that I can buy the parts and beer and get started fixing it. Thanks in advance. p.s. I have been a member for years but I just read because I can't type worth a #$@%.

[catmandoo]

i have the same problem and mine only does it after coasting for 1/3 to 1/2 mile like if i'm cruisin down the freeway and come to my off ramp i'll pop it into neurtal and coast up to the stop sign. when i take off in first and at about 15mph just before i shift it surges and throws ya back in the seat then when i let the clutch out in second it's still pulling .then again on a few occasions its been really sluggish in second. it was suggested to me by brittanic to check cdr valve for oil well i replaced it and still does it i've just come to live with it and if i do coast when i take off i just shift before it has a chance to do it. i've also been told it could be a worn governor in the pump?whether or not this could be i don't know but i do know that feeling. wish to ole diesel ran like that all the time,now thats power .

[billg]

Hi Lineman,
Doesn

[britannic]

Also check CDR operation, by using a clear tube bent into a "U" with engine oil in it, plug that into the engine oil dipstick tube and see what happens when the engine is revved. The oil should be drawn 1" or so toward the dipstick tube. If the oil moves away from the dipstick tube, doesn't move, or you have bubbles, then the CDR is probably not working and allowing enough oil into the engine that it ignites and make power, without any control from the driver.

YMMV, I had the exact symptoms you describe on my mechanical 4911 engine, but obviously the DS4/computer control system is a further complication, so eliminate the CDR as the problem first, since it's the cheapest component .

[lineman]

Hey guys, thanks for the ideas.The CDR seems to be a good place to start at.I talked with the tech at the Stanadyne place where I got the inj. pump and he suggested the CDR along with the oil pressure cutoff switch.He said it controls the lift pump.He said it sounds like air sucking in the system at higher RPM's.I told him that I had never changed out the CDR .He told me to start there, because they should be changed out ever 40K.Keep sending ideas and I'll let ya'll know if it works or not.Sounds like a one or two beer job. Lineman (member #1414)

[catmandoo]

don't know how they are to get at with the turbo but my n/a i didn't even get a chance to pop a beer, like a 2 minute job.

[lineman]

My Redhead won't know the difference anyway.I need a good reason to be out side,She's been riding a broom ( turbo charged ) lately.

[lineman]

Well,I found out what the problem was.I changed out the CDR before leaving work yesterday and all the problems were still there. So this morning before my boys baseball game at Little Rock, I changed out the oil pressure switch. Just as soon as I started the truck (Cold start) I knew it was fixed.The ole truck idled perfect. On the trip to town it was like a new truck.The 50hp was there all the time.When I got back home, I checked the fast idle solenoid and it was bad.I will change this out this week when I get time to pick one up.This should take care of the super hi idle problem that I have been having.Thanks Britannic and Billg for the suggestions.O BTW the CDR with 173000k miles was perfectly clean inside,I mean sparkling clean.I guess the Rotella is doing it's job well. Later..... Lineman