Per the dealer the injection pump on my 03 is running at half the pressure it is suppose to. I cannot find any info on this site about injection pump failures for the Duramax. Lots for the 6.2 and 6.5 but not the dmax.

Has anyone else heard of injection pump failures?

I was getting temp increases up to about 230-240 and had been down all the other tracts like thermostats, fan clutch, etc. The increases only occurred loaded on grades. The truck was also downshifting and staying in a lower gear a long time and like it didn't have the power to get it up to speed. My fuel mileage was horrible the whole trip. the truck felt like it was loaded to about 40,000 lbs because it was so sluggish.

Mech called tech line and they said the low fuel injection pump pressure was causing a lean mixture which was increasing eng temp. It makes sense in light of the other things going on at the same time.

I will soon know if that was the problem.

Same thing happened to me over the nice long weekend pulling a camp trailer fully loaded, going up a long grade I saw temps into the 240's. Only happened on the really long steep grades though. :( Had a feeling something was wrong when I couldn't pass a Powerstroke with half the load going up the same hill.:)

Keep us informed on this. I also suspect fuel quality is going down the tube on us.

I am leaving in the morning to pickup a 5th wheel in San Antonio and take it to South Jordan, UT. I will know if the problem is resolved by tomorrow afternoon.

I would also like to see what happens. Last weekend I pulled my 5er (13000lbs) about 150 miles in 90 degree temps. It is up hill half way, then downhill halfway. Ran fine heading out. On the way back it would not pull over 60 mph and was running 230-250 on temps. This is a long slow climb till the last 1.5 miles which is a 5% grade. I had to pull over and let it cool down before the last 1.5 miles climb. I noticed once on the other side everything was ok for a while, but after pulling in and washing the truck and trailer, it was very sluggish. I nailed it out of the car wash and if was slow and by the time I hit 65 it was running 240 already. Most of the climb was at 45 mph which is terrible.

Nice to meet you today Tom!! Hope the fix works for you!!
:)

Have you noticed more noise with the loss of fuel pressure? I was thinking that the pilot injection may not work as well with lower fuel pressure. I have also noted loss of power, running warm (not above 210 on the guage) little noisy but no fuel in oil or smoke to make me believe that it is injectors. I was thinking the other day if low fuel pressure could also cause some of these symptoms.

My rail psi was down to 16,900 actual at WOT it was commanding 23k i'm picking it up today we'll see if the new pump helps. dave

all sound like symptoms of the injector pump.

Injection pump failure sounds correct, but your mechanic's reasoning is wrong. You can't create a lean condition in a diesel and harm it. ECT temp should go down with lower fuel volume.

I am leaving in the morning to pickup a 5th wheel in San Antonio and take it to South Jordan, UT. I will know if the problem is resolved by tomorrow afternoon.

Any news yet for us Tom

brayden, lower fuel pressure would be like dribble, fuel burning out exhaust since it didn't fully atomize at peak time, and raise temp.

Finally got back to where I could reply.

The performance issues were solved with the injection pump. I did still occassionally have high temps. It was not as bad as before pump replacement because the truck was not downshiffing and was able to pull grades after the pump was replaced.

I had temps in the 230-245 range on real long pulls in high outside temps but they would drop back if I turned off cruise and let the egt back off to about 1200 deg or so. It is a little scary when the engine temp goes up that high but supposedly that is within the operating range.

On this trip I had a new Edge Attitude that was a replacement upgrade for my old Edge. It sure performs better than the old chip. I run the Attitude on level 1 and it runs great. No need for more when towing. It got rid of a nuissance I had with the eng or trans (I could never be sure which it was but probably trans). It seemed like a gas engine plug would misfire and the it skip a beat. This would happen on hills with cruise control on. It always concerned me but had no way of duplicating it since it happen periodically and no way to point to what it was. Apparently it was a chip issue and it has not done it since the new one was installed.

I went on to UT after I met Rick in NM at a rest area. I enjoyed talking you Rick.

After I dropped in UT and went back to OK and then to AL and stayed there hauling to FL, GA and upper AL for over a week. Never saw anymore high temps, only humid as that part of the country usually is.

Another desert run will tell me if I have a temp problem. I believe I have some injectors failing again though. White smoke at idle, just like when the other 3 sets failed.

Who makes aftermarket injectors for the dmax?