Okay, I bought the truck from the company, Dealer said it was the Optical Sensor, and the whole IP would need replaced to the tune of 2400 dollars. they said no and decided to get a new truck, i bought this one.
It will seem to run okay, then as soon as its under a load such as a decent hill, it will hesitate and miss, also completely die for a second or two, then restart. after a few rounds of this it will kick into limp home mode, and have a max speed of 25mph. also has refused to start on several occasions, sometimes after a 15-20 min. drive, some times for no reason at all after sitting all night or day.

1.Lift pump test (http://dieselplace.com/forum/showthread.php?t=39350)- describe results;
Passes, replaced recently kinda as a shot in the dark that didn't hit anything...

2.Service Engine Light - on/off/intermittent
On, Codes
P0251 IP CAM System,
P0370 Timing Refrence High Resolution,
P1216 Fuel Soleniod Responce Too Short,
P0251 again, and P0370 also

3.Model year;
1996


3a. Odometer reading;
149,000

3b. Miles on major engine components if been replaced;
In dealership last augest, changed Injector driver...

4.Do you have any engine codes? Yes or No.;
Yes, See above

5.If you do have engine codes - what are they?

6.Air Filter condition (visual check)
Like new

7.Fuel filter condition (freshly changed or condition unknown)
Changed recently, about 2 tanks ago

8.Condition of Battery terminal connections (cleaned and tightened)
Clean and tight

8A.Known condition and age of the batteries.
Batteries good, replaced about 2 months ago

8B.Are batteries of differing age or are they a matched set?
Matched set

9.Upon cold start, does the radiator hose get hard quickly? Yes/no
No

10.Upon cold start, do you have excessive white smoke? Yes/no
Puff at start up but clears right away

11.Do you have excessive cranking time before the engine starts?
Not when it starts. Sometimes it will run for a second or 2 then die, and have trouble starting again. turning key off for 30 seconds or so usually cures it and it will start afterwards

12.Have you used the block heater, and does this effect engine starting?
No but it sits in a 60 deg garage overnight, then gets moved outside during the day where it sits in the cold, then moved back inside, and starts the same either way

13.During hard acceleration, do you have excessive black smoke? Yes/no
Yes, but only during "limp home" mode after it's rethrown the codes mentioned above, but before the SES light comes back on, it will run okay, hesitate, and stumble, then run okay, then repeat and throw on the light, and then will smoke

14.Do you have any unusual exhaust smoke issues?
Is this a trick question?

15.Turbo check out (http://dieselplace.com/forum/showthread.php?t=39368)- pass/fail
Pass

16.Do you have an EGR on the engine? (An F or an S engine code)
No its an "F" engine

17.Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD.
2500HD (8200gvwr)

18.Indicate fuel that you are using: Bio-diesel, #2 Diesel, #1Diesel, SVO/WVO, other;
Straight Diesel, probably winter blend, hasn't moved far in a while, maybe last fill up was mid fall.

19.Are you using any fuel additives? If so, please list.
None

20.Please indicate geographic region you are in: (example: Texas or Canada)
North eastern Ohio

21.Do you have any service history available that might pertain to the problem you are having?
Truck has been excelent and problem free minus some recall on the turbo system when 1 year old, and has had the alt and both batteries replaced within the last 3 months. untill about 8-10 months ago, went in last augest they replaced the injector pump driver seemed to fix it, but problem is back and is exactly what it went in for in august, now they say it's the Optical Sensor

22.Please indicate any modifications to the vehicle that might help us diagnose better.
Reading utility bed and seat covers ):h otherwise exactly as GM shiped it out

23.Upon unscrewing the fuel cap (http://dieselplace.com/forum/showthread.php?t=42338), do you have a large vacuum formed in the tank? yes/no
Yes, left it loose but seems no change

24.Location of PMD/FSD (http://www.dieselplace.com/forum/showthread.php?t=39436)? On the pump/remoted over intake/remoted out of engine bay (please specify specifically)
Exactly where GM put it

25.Are ALL glow plugs in proper working order as per this thread (http://www.dieselplace.com/forum/showthread.php?t=39182)?
Yes


Okay thats about it. Should I just change the optical sensor? or do you guys think there is an underlying issue?

TIA
Trapper

Welcome to the forum, big............

P1216 indicates a problem with the fuel, or the fuel supply - bubbles in the fuel can cause that.

The other two indicate PCM ain't happy with what it's seeing in the pump - could be dirty or cloudy fuel confusing the Optic Sensor.

Opening the water drain tap should not kill the engine, and the fuel out should be clean and clear.

Your symptoms sorta indicate problems with the fuel

Optical sensor filter harness still in place? Try removing it, (plug in direct with out it) and see if the results stay the same.

well, looked at it some after work, drained some fuel into a jar, had particles in it. thought I cleaned the jar... dumped it out, re-cleaned it, and same results. grabbed a fuel filter off the shelf, changed it out, the one i replaced was as black as this text. SOBs at the dealership never even opened the damn thing let alone changed it. you would think before reccommend 2500 dollars worth of work you'd change the damn filter, or at least LOOK at it. I work for a company that uses JD diesels, a 4.8L generator, and a 12.5L for a vaccuum pump. if I go out on a service call, the FIRST thing i do, wether or not they need it is change fuel filters on BOTH motors. I'm still amazed at how many electrical problems are related to a dirty fuel filter. I changed the filter, bled the lines and fired her up. ran better than it has in a LONG time. tommorow i'll take her for a spin and see how she's going, and clear the codes as well and see if any come back.

I'll update later after i take it out for a spin and *hopefully* verify that it's fixed. Thanks!

well truck fixed! changed fuel filter SES light went out today, kinda rough start today but it was only like 25* for a high. lots of power, and she's back in biz! I'm gonna swap the OEM bed back on tommorow and bring her home! amazing what a fuel filter will do. especially since the dealer wanted to charge 2300 dollars to change the IP when the (insert bad word here) didn't even check the fuel filter. sorry but that still pisses me off, thats just plain terrible service.

service seems to be a thing of the past these days though...

The old time mechanic is a thing of the past, especially at a dealership. They scan for codes and do what the book says, which isn't always the right thing and NEVER is the cheapest thing.

Congrats to you for fixing the problem.

Dave

good job, that would be the first thing i do, and i still check the filter on the machines i work on.

okay, truck ran great for 2 hrs last night, put 70 miles on it. about 40 miles into it lost power and the SES light came back on. shut it off, started it back up, ran normal for a while and after a few on-off cycles stopping at various places, the light went out, then would throw the code and had this happen a few times. stopped and put fuel in it, went in and bought some "Howards Lubricant" and put in it and filled it up. gas cap was under crazy vaccuum. started it up, it stalled immeidately. restarted it ran decent then cleared up. drove home, about 2 min from the house it studdered and went into low power mode again.

well went out today and cleared all codes via autotap, took it for a ride, and the only reoccuring code is 0251 IP CAM system. I'm going to change the fuel filter again and see how it looks today. but i'm thinkin i'm gonna have to throw an IP in it anyways. Let me know what you guys think.

TIA

Trapper

Sounds like PMD/FSD to me. For a couple of hundred bucks for a new one, get a heat sink and extension harness or go with the Heath Kit which comes with everything. If it's not shot now, it will be before too long if left on the pump.

Dave

Fuel issue again ... that high vacuum in the 'gas' cap is a problem. Make sure the thing is vented (fix or replace the 'gas' cap with a 'fuel' cap), make sure your lift pump is working.

When you change the filter again, check and clean the bowl and housing ... what's IN there?). If you get it all cleaned up again and the stuff comes back, you have tank/sock issues and may need to clean that (ugh).

Fuel issues are mostly cheap to solve... not easy, but cheap. Look into them before going for a PMD solution.

If fuel supply issues don't turn up anything, I'd try a driver before an IP in total, get one with a warranty so it will be last one on your dime for a long time.

Okay, changed the filter, again, but it was perfect, almost same color as the new one, probably just because it was wet. Tried to remove the optical filter, but the oppiset end is stuck under the lower intake... The sticker on the harness was melted and you could tell the wires are hot, also the sticker on the side of the optical pickup was shrunken and blank from heat as well.

And by Driver you mean PMD/FSD right? I'll order one of those up today.

Yep, by driver, he means FSD/PMD and by one with "warranty", I believe he would be talking about Heath's set up. 7 yr warranty.

Dave

cool, orderin it today. really seems like it, it's all good when the truck is cold or when i'm driving it. but if i park it hot and go into a store for a time, it acts up when i come back out, assuming it's heat soaked by then and thats whats causing the problems. let ya know how it works out.

Sounds similar what was happening with mine before I replaced the PMD/FSD.

Hopefully it works out for you and like I said. If it's not dead now, it's inevitable that it will be soon.

Dave

I've a Heath remote FSD and am tremendously happy with it. Add the fuel filter date to your sig if you don't maintain a record. If you think about it, gassers have their expendable parts and so do diesels - you're paying for them so maintain a positive view on your truck. You're doing the right thing but keep reading; this site will prepare you to keep your perfectly good vehicle running.

Well, Changed the Optical Sensor, problem solved! Do they always try like hell to talk you out of doing this yourself when you buy a replacement? it was incredably simple and after i got done and it literally fired right up all i could think is "you've got to be kidding me? that was what is so impossible to do yourself?". So now I have another brand new PMD sittin here, came in a day too late. I'm gonna throw the 9 resistor in her anyways. I had pulled the service records on the truck, had a new PMD put in in august so i kinda rulled that out and opted to swap the OS first.

anyways! Truck runs great and I"m stupidly happy with it! rides great, interiors great, whole truck is awesome! Very happy with it.
Except one thing. really wish she was 4wd... had some snow here today and Remembered really quickly why i have yet to own a 2wd truck. maybe that could be next summers project, airbags all the way around, 38's and a Solid front axle, anyone know what transfercases will bolt up to a 4l80e :lol:

Thanks for everyone help!

Yep, I thought they were going to make me sign a waver.

Told me on the phone and then again at the shop. Did not offer any info of what could happen and I didn't ask.

Here's a question for ya,

Does your truck seem smoother now when your holding a steady speed then it did with the failing OS?

I would not really call it a miss but it just seemed like it was not smooth before I changed it.

Definatly much smoother, easier to start as well. still kinda baffeled why GM won't swap this on there own and wants to sell you a whole new IP...

I got mine at a local injection service company and they insist it can't be done.

I'm sure there is a super fine adjustment on the thing with not much tolerance.

I guess it could just go out of control at any second if your right on the edge.

I used to use magnetic tape drives that had optical couplers. They would go berserk and start spinning out of control.