Diesel stalling, bad performance

[mzllo dr]

Just bought my first diesel, 1995 6.5LTD, GMC, ext. cab, 4x4, 175,000 miles. I have a
problem(s) and I sure could use some help.
THIS SUMMER:
Typical problem, truck starts O.K. cold, but when warm it starts and then in a few seconds dies. Especially about the time I pull it into drive. Won't restart unless it cools down, or I pour cold water on the PMD. (I'm not happy doing this).
I have read the "fix" is to replace and relocate the PMD away from the injector pump into a cooler area. Everyone says that I have to have the intake manifold removed to remove the present PMD.
Can't I just unplug the wires from the present PMD, leave it attached to the injector pump and abandon it and reconnect the wires to a new PMD at a new location and save having to remove the manifold ??
NOW, THIS FALL:
Cold starts O.K., rare that it dies on a hot start. But, pulling on a long, steep grade, empty, it feels like the engine hits a governor or something, flattens out, seems to lack further power, the "Check Engine Lite" comes on and stays on until I am almost down the other side of the grade. If I really open the throttle from a standing start it sporadically misses and jerks until about 55 mph, 2400 rpm. If I am going up a long steep grade now and really open the throttle it misses and jerks really bad. Especially if it down shifts and raises the rpm. I was getting 15-16 mpg running highway, empty. I hooked up my 24' pontoon boat today, drove 200 miles in 3rd gear (manual says no overdrive pulling) and when I re-filled it I only got 8.3 mpg. Also, at 65 mph I was indicating one bar below "red line" on the tach. If I went 70 mph I would be into the "red line".
Now that the weather is cool the "Check Engine Lite" comes on as soon as I cold start it, and stays on until the engine warms up.
Very recently the "Check Engine Light" comes on randomly as I drive at highway speeds, stays on for 1-5 minutes, then goes out. Sometimes this happens if I lift my foot from the throttle, sometimes just running level.
I took it to a highly recommended diesel mechanic shop last summer for the hot start problem, only codes or things he could find after keeping it and driving it for 2 days and catching it on his computer during a hot start "die" was that the crankshaft rotation sensor was bad, and he replaced it. It didn't help. He said it might not fix the problem, he is baffled and he said if I can find any suggestions or fixes, he is certainly open. This mechanic shop is the best in Des Moines Iowa, and from a long way around.
As far as I know, from the orig. owner, the injectors have never been changed. The injector pump was changed at 80,000 miles.
I'm using Howes Lubricator for lube and anti-gel.
I love the diesel, if I could get it to run.
I would appreciate any help and suggestions from you guys who are much more diesel knowledgable than I am. Besides the PMD, am I having injector pump problems AND injector problems, or what do I have here.
Thanks to all.
Dick Brees

[moondoggie]

Good Day!

The 1st & best thing you can do is order all the reprints of The Diesel Page. These types of problems have been covered extensively in the articles contained. There are six. At $20 each (I think) you

[john8662]

Just a thought, but to help us troubleshoot the check engine light problems we are going to need to know what codes are stored on the computer that turns on the check light or SES (Service Engine Soon) light. To check codes go here:

http://www.thedieselpage.com/members/trblcode.htm

There are instructions on how to perform the task. You have a 95 model, so this is the last year you can check for codes without a scan tool. You just count the SES light blinks on the dash while performing the procedure.

[patrick m.]

the flat spot that you hit is the wastegate opening, the s.e.s light is most likely a code 78, w/g solenoid fault. check the vac hose from vac pump, to solenoid, to wastegate actuator they like to split/crack.
if vac tube is good, check operation of solenoid, eng at idle you should have vac at actuator.

check codes, and re-post.
replace the oil pressure switch, this will get rid of your "eng miss".
replace your ignition switch, the electrical part, not the key cylinder. this is a guess, but a good one for your stalling because you have a '95 model. even if the switch is not your problem now, it will be in the future.

1) check codes
2) check vac tubes to wastegate act
3) replace oil psi switch (there is a relay kit you can put in this ckt--check the top posts)
4) replace ign switch

after these four steps you should have the majority of your problems eliminated
let us know how it goes.
Patrick

[charliepeterson]

A lot of you're symptoms seem like fuel issues unfortuneately this could get expensive. The reprints are an excellent idea.
The first thing to do when diagnosing these problems is to change the fuel filter. This helps in seeing what kind of fuel (dirty/clean) you're running on. When you're bleeding the air out you can tell if the lift pump is working now, very important.
Now you need the engine codes if any. #'s 18,35,36 are the worst. These are deadly to the Injection Pump.
Relocating the PMD/FSD is a very good idea. This little box creats a tremendous amount of heat which the injection pump doesn't need. A good dose of fuel conditioner ounce in a while is also good. I personally dont like to run the tank down too low. Any debris inside stays in suspension better and the tank acts like a heat sink for the injection pump. The fuel is all that cools and lubes the injection pump.

After the codes are pulled we can help much better.

[dieseldaver]

That stumbling/sputtering at full throttle sounds like the lift pump might not be working. It's easy to check. With the engine idling, just open the little valve thingy on the top of the fuel filter. If nothing comes out, it's not working, if it sprays out, it's working. If it's not working, it's likely one of two things, either the lift pump is broken, or the oil pressure switch is broken. Both are common. See the notes above for more detail on these. If it's not working, the injection pump will suction the fuel out of the tank okay in normal operation, but when you stomp on it, you starve it, creating the stall/sputter condition. Make sure you fix it. If you run it for too long without the lift pump running, it can burn out the injection pump faster.