Sorry for the long post, I wanted to be thorough. Unfortunately, my truck has stumped many a mechanic. I am to the point of extreme frustration. I have replaced many parts, some of them repeatedly, only to find no improvement in performance. IP's are expensive.

Current problems: 1. Lack of power. 2. Major ammounts of black smoke on acceleration. 3. Engine hesitation. 4. Engine stall/prolonged crank time to restart. 5. code 78 pops up after driving 65mph/3000 rpm, overdrive locked out.

I have had codes: 13,31,32,33,34,35,45,78, and 99
History: As best as I can remember.
11-01 New Vac pump, EGR, no change in performance
01-02 New IP, Still had hesitation, black smoke ok.
11-02 Direct wired lift pump to turn signal, hesitation fixed, black smoke ok.
08-03 Replaced selenoids, Vac lines & harness, No change.
07-04 Replaced WG selenoid, EGR vent selenoid, center selenoid, control selenoid.
09-04 Replaced IP
05-05 Replace ECM
07-05 Replaced accelerator postion sensor

Please forgive my "silly girl" questions. Is the lift pump supposed to run constantly while engine is running? I thought it might be contributing to black smoke problem, so I disconnected it. But it seems that it has caused more stalling/hard start. So I think I will reconnect it, and look elsewhere for lack of power/black smoke solution. Which codes will show when lift pump is not working properly? How long should a OPS last? Will EGR or Vac problems cause IP to fail? Are any of, or how, are the above problems related? Is the WG something that continues to fail? How could I tell if the dealers are just seeing a skirt and taking me for a ride? They want to replace the vac pump again.

Thanks for your help, I am so glad to find this site!http://www.dieselplace.com/forum/images/smilies/smile.gif

Your lack of power and black smoke could be low boost pressure. You'll have to work with the vac system till you get it right. Since you have an EGR, just putting an adjustable spring on the turbo doesn't solve all your problems. A vac pump a year is not uncommon. I have one or two I'll never use again.

Keep the lift pump working, the IP requires it.

Are these current codes? or just a history of codes that you've had in the past?

Codes are: (from Kennedydiesel.com)
DTC 13 - Engine Shutoff Solenoid Circuit Fault
DTC 31 - EGR Control Pressure/Baro Sensor Circuit Low (High Vacuum)
DTC 32 - EGR Circuit Error
DTC 33 - EGR Control Pressure/Baro Sensor Circuit High
DTC 34 - Injection Timing Stepper Motor Fault
DTC 35 - Injection Pulse Width Error (Response Time Short)
DTC 45 - EGR Vent Error
DTC 78 - Turbo Wastegate Solenoid Fault
DTC 99 - Accelerator Pedal Position 2 (5 Volt Reference Fault)

You've got a mess of lottery numbers there. There is a common theme there with the vacuum system. Do you have a vacuum gauge? Check to see what the pump is doing, AND if you have vacuum leaks somewhere. If you have a new pump, it may just be leaking.

If you've been blowing black smoke for a long time, your cat (Cat. converter) may be plugged up too. This will lead to lack of power because of a hindered exhaust system.

One other ever popular cause of problems is the engine ground. It's always a cheapy check, even if not the source of your problems, it's always good to clean up. With all the electronics, you never want to chance it being something that simple, and pull your hair out with other more expensive things. Look for the braided cable between passenger side head and the firewall. Remove/clean/reinstall. Just do it, even if it looks okay.

The only current code I have is 78. The shop cleared it today but it will reset if I get it up to 3000 rpm. I am not familiar with the Vacuum pump, just what exactly does it do? Is it a necessary part of the system? From reading posts on here I am guessing that the Vac runs the EGR and WG.

That's right. The vacuum pump closes the waste gate (DTC 78) and opens the EGR. There's three solenoids that meter the vacuum and the barometer on the firewall looks for ~20" vacuum at idle as well.

DTC 78 at 3000 rpm could be the wg solenoid but you'd have to check for vacuum to determine what was wrong.

What part of the country are you in Ms Blues?

Try to unbolt the cat or remove it altogether, it may be plugged almost solid. I've seen many a gasser stall and die because it was plugged, don't know if the diesel will have the same effect. Re-starts when cool were no problem but once it was heated up the truck would stall. Five minutes with a hammer and a punch and my truck was running fine again, cat got tossed after work and it ran fine.

I went to the parts store and bought a repair manual. I located the selenoids, egr, map sensor, and watse gate actuator. I start it up and start pulling off vacuum hoses. NOTHING! Not one bit of vac pressure. I did not pull the hose directly off the vacuum pump, too close to fan for my comfort. So if a vacuum is not necessary for the engine to run what could power the waste gate? Or is the turbo just supposed to run on it's own? And the egr just reburns recyled fuel right? Seems that this would be undesirable since your just putting a bunch of junk back into the chamber right? So that leaves the map sensor. What does that do? I lso found oily residue in theplastic connector that goes from turbo to air filter. What does that mean? So I am pretty hot now and some poor mechanic is getting my truck shoved up his business end. I just got charged for a new throttle sensor assembly and ECM, but it never occured to them to check the vacuum. Something so simple, even I could do it.

You don't have to have the vac or EGR to run the vehicle but it does require slight modification of the intake and prom to change as S engine to an F engine.

Oil in the air box from the CDRV is to be expected.

The vacuum tubing can become leaky, so you should check for vacuum at the larger rubber outlet of the pump. If you've got no vacuum there, the pump is probably gone, and you'll need either a new one or go for mechanical boost control.

You can tell the status of the wastegate by looking at the wastegate lever. The lever must be pulled tightly up at idle; if it is not, the wastegate stays open and you'll have no/insufficient boost pressure.

You can also have broken wires going to the solenoids. They can set codes with OBDII, but don't neccessesarily do that. I've had a broken vacuum pump and a wire to the WG solenoid that was broken several times, so some months after replacing the pump and repairing the wires, I could see having insufficient boost on the gauge long before codes were set. I had to repair the wires a second time to fix it. Gauges are essential ...

The EGR routes exhaust gas, not fuel, back into the air intake. The intake will become sooty from that.

Is it safe to check this while engine is running. I would like to save my arm from being sheared off. And I don't need any 3rd degree burns either.
Oh yeah... The actuator lever is very movable. Which way is open/closed? The part that it swings on is in a vertical position but can be moved to an angled position also.

Went outside and fired up dad's truck. His is a 95 with only 90k on it that he has lent to me since mine's been in the shop off and on for the last tow weeks. And I could definately feel vaccum on that one. The vaccump pump is located just below the a/c compressor right? There is a tube that comes out of it on the passenger side and goes right back in. Is that where I should check for pressure? I can't get to the smaller lines that go out to selenoids without injury, or can I?

Wastegate lever fully up is fully closed, max. boost.

Sorry, I didn't think of the '94s having a different setup! The alternator and vacuum pump on mine are on a bracket at the passenger side, AC compressor is on drivers side.

There's such a tube on mine, coming out the pump and going back in, but that is _not_ where you should check for vacuum. There must be another such tube, about 3--4 inches long, coming out of the pump, and a thin plastic tube should be plugged into it (unless the pumps on the '94s are much different).

Wait a few minutes, I'll take a pic of my broken pump and post it here.

pump outlet --- there's a rubber tube connecting the pump to the rest of the vacuum system, I've taken it off the old pump, put it onto the new one and plugged the outlet with the plug from the new pump

Do you think you can get savely at the outlet tube? If not, you could try using some tube you know not to be leaking.

But since you've two trucks at hand, you could take the pump off your fathers truck and try it on yours. These pumps are rather expensive.

Overview --- pulley is on the right side, outlet left, the 'runaround' tube on bottom.

the 'runaround' tube

Yeah I olee I can get to that runaround tube. There are no other hoses connected to it. They come in somwhere on the other side I can't see them because a/c is in the way. Thanks for going to all the trouble to post pics.

Ja, the 'runaround tube' is on the front of the pump where the pulley is, the outlet is on the rear side. Maybe someone with a '94 can tell how to get at the outlet. I imagine it could be possible from under the truck, maybe from the drivers side wheel along the axle. If you can get there with some engineers pliers, you might be able to loosen the hose clamp on the outlet and attach your own tube.

Taking the pics wasn't much trouble; I happened to have the camera and the pump around.

First I tried taking off the runarround hose, truck wouldn't start. Also that tube is missing a little rubber where it fits inside. So I plugged it back in and then I looked on the other side and fount the line had a splice in it, so I could disconnect it without having to get too far in and close to the pulleys. No vac there either. Looks like the pump is cooked. I took some pics but aol has hi-jacked a: drive. I wouldn't want to go through all the trouble to borrow dad's pump. If it comes down to working on it myself I am going to need the least hassle possible.