Hard start, cranks easily though when it finally does start it will hardly stay on If I work with it I can get it to Idle up to about 2700 rpm and at that point the truck will accelerate some what normally and the check engine light is on. I can drive it that way very low on power The truck is reading computer codes 18 & 19 seems everyone is an expert, I have fuel, I am not Jelled I have good pressure at the filter canister

If I shut down the truck I go through the whole process again so I can drive it while the check engine light is on the RPM runs at idle around 8000 rpm which is higher the normal os right around 6000
any knowledge would be greatly appreciated Thank you so much for your help
Mike

 

95 is a 6.5 TD,Duramax did not come out until 2001,get PMD and relocation kit.

 

Hey Buddy thanks for the reply now at showing my own stupidity What exactly is a PMD and why all the sudden after 319000 miles does this need to be completed ?
Thank you
Mike

 

I think your reading the tach wrong! 800 is not 8000.

 

Scroll down a little further to the 6.2-6.5 section and you will find all the info you need.

 

Nice

 

Hey everyone here we go again! I replaced PMD and for $280 I was able to loose code 19 still have code 18 noticed that my cruise control quit working at the same time I am having very hard starts and have to chug it up to higher rpm while blowing enough smoke to kill all insects and once the check engine light is on it clears up and idles great have more power than when I had Old PMD but kind of chokes when I get to higher rpms when getting into it acts like a govern er Kinda broke and really need my tuuck back bad Please help A friend of mine said it could be a pump control module the lil thing on top the ip with the plug. any ideas or any info on how hard or expensive it its to change?
Thanks
Mike

 

With the lift pump jumped to run:
Start with the basics. Get a gallon glass jar and run 3/4 Gallon out the T drain while noting the flow - how long does it take you to pump out 1/2 gallon? - and looking for crud. Let the jug sit for 20 minutes or so and see if water bubbles have formed on the bottom of the jar

Change your fuel filter/ I clean the bottom of the bowl out with an electric fuel pump. Then I add some SEa Foam & use a flux brush to clean the bowl more if needed, before I suck it out again.
Pour some Sea Foam in the bowl before you re-install the new filter.
Check you air filter, oil and coolant.
Make sure you bleed the T valve and filter after changing the fuel filter.

---AutoMerged DoublePost---

On a 1995 you need to do the dual lift pump relay upgrade. It also gives you a good place to jumper the lift pump for diagnostics and priming.

There are many possible causes of your issues. Need to start eliminating them.

Could be a bad fuel line or 3. Could be the fuel filter manager - the fuel filter housing sometimes develops a leak.
Could be a plugged tank sock.
Does the truck ever run good anymore?

---AutoMerged DoublePost---

great white

1 posts, read 5,850 times
Reputation: 11
Thread is a bit old, but I'll chuck it out just in case the OP is still struggling with it.

Code P0251 is indeed related to the injector pump optical sensor.

However, it's not always as bad as some think. There can be a few causes for this code. I'll try to put this in as much layman's terms as I can, as it can get quite technical:

In a nutshell, the PCM sees and error in the optical sensor functioning.

The optical sensor functions by "looking" thorough a spinning disc in the IP that has "windows" in it. The PCM uses this signal to properly time the injection events to the crank rotation and in turn the piston's rise and fall.

When the sensor has a problem "seeing" though these windows, the PCM sets a code p0251.

The Optical sensor is calibrated to "look through" clean straw colored diesel fuel. It can't see though air at all and doesn't deal well with water, bubbles or some fuel contaminants that make the fuel too dark. These conditions will cause it's signal to fail and set a p0251.

Causes of these things can be air getting into the system, weak or dead lift pump, water in the fuel, running very low on fuel or running out, etc.

Check out your lift pump and see if it is running and giving you around 7-9 psi static. It shouldn't drop below roughly 4-5 psi at WOT.

Check to see if you're getting air in the system. You can run a clear house on the water drain line and pump some fuel through it. If you see a steady stream of any sized bubbles, you have a pinhole or other sized hole somewhere between the filter manager and the tank. This can be a real bummer to hunt down....

Another possible cause is the optical sensor filter harness. These are notorious for failing. chek the wiring harness coming out of the optical sensor and the filter harness will look like a little box in the wiring. 96+ trucks had this filter incorporated into the PCM so you can just unplug it and toss it in the trash. For some reason, GM kept installing in it in these trucks even though the redesigned the PCM. The wiring harness is still long enough pull it up and plug it directly into the optical sensor and the 96+ trucks run just fine without.

Lastly, it can be a failure of the optical sensor components. If the sensor itself has failed, it can be replaced, but there are some very specific procedures that need to be followed. The optical sensor is set up when stanadyne builds/rebuilds the pump on a test rig. Get it wrong and all kinds of drivability problems can arise such as super sensitive throttle. It's not cheap either, somewhere around 350 bucks.

If the IP disc (spinning thing with the windows) is damaged, you have to replace the IP assembly. This is a pretty good shock to the wallet. Depending on where you get one, it can be anywhere from $500 to $2000. Stay away from anyone who is not an authorized rebuilder (the $500 guys). They almost always cut corners, use old worn parts, don't swap in the updated Stanadyne pieces (ceramic pistons and rollers to better deal with ULSD, etc) and don't have the proper test equipment.


Read more: 1996 Chevy 6.5L turbo diesel - P0251 Injection Pump Metering Control A (fuel, best) - Sports cars, sedans, coupes, SUVs, trucks, motorcycles, tickets, dealers, repairs, gasoline, drivers... - City-Data Forum

1996 Chevy 6.5L turbo diesel - P0251 Injection Pump Metering Control A (fuel, best) - Sports cars, sedans, coupes, SUVs, trucks, motorcycles, tickets, dealers, repairs, gasoline, drivers... - City-Data Forum

 

Thanks Jeff I have a lot of time to look thru this stuff as I burnt up my starter yesterday cranking on it like a fool It still will turn over but acts like its got a dead battery and I had some smoke coming up by my dip stick for the trans. I am rather pissed and mad at my self but some one has to be an idiot guess it was me yesterday. I dont know what I was thinking went and bought a battery charger and charged up the batteries but the temp is down to 29 degrees and I didnt have the block plugged in so still turning over as a dead battery (2) but there full charged
Ill be in touch again soon I just need to get some fundage I think before I can move forward again