2007 GMC Medium Duty with 7.8L Isuzu Engine

[GregCrabb]

I know this is a totally different engine made in a totally different country and does completely different work from yours....but....my Volkswagen diesel was doing the exact same thing your Truck is doing....and it was my ECU simply telling my turbo not to boost. The engine would start fine, idle fine, drive fine until around 25 mph, then it was as though the bottom fell out and it would crawl. It took my dealership a month to finally figure it out, but after I got a new ECU under warranty, it has been fine since, knock on wood. Just a thought. Mine would always act up on my interstate drive to work in bumper to bumper traffic at 70 mph...and my car would be struggling to do 45. They first thought it was the EGR sticking, then the MAF sensor.

Like I said though, I know my engine is not like yours.

[scooper]

Thanks for the info about your volkswagon, but the engineers changed all the sensors, 6 injectors, two ECM's, two emission pipes, still doing the same thing, that is when they decided to give us a new engine. Our old engine only has 20,000 miles on it. Bucking, jerking, loss of power, basically from day one, not as bad, but got progressively worse. First oil change at 5000 miles, oil real black, secondary fuel filter really black in the vanes of the paper filter.
Alot of carbon, I would think.

[Mark Rinker]

Fuel filter really black? Ummm...where are you getting your fuel??? As I said in the first post - bucking/jerking sure sounds fuel related. Now you report your secondary fuel filter is black? A lot of carbon? In your fuel?

Better get that one figured out - before you feed a brand new engine the same fuel that killed the first one.

[murphyslaw]

sorry to hear of your problems.

I have an '03 6500, it has been a great truck.

It did go into limp once. I was unloaded and going up a hill that I went up everyday and just dropped to idle and the SES light came on. I pulled over shut it off for about 2min started it back up and have put about 30k on it since. and this happened at 88k.

if your fuel filter is black you have fuel quality problems.

[yak4500guru]

Hey,
Lemon law that thing! Im a GM dealer and diesel fanatic and im telling you the commercial LL suits are easier to win. The truck is costing you money because you use it for work, right? Well your thread spiked an interst so i asked my friend who is a heavy line Isuzu and Duamax wrench your questions. If you want to ask him yourself look up redline performance diesel in corona california these guys are the R and D company for RBP. They know their Sh@t if you know what i mean. he told me fuel jelling or particulate matter clogging the rails. Hey GM will stand buy the truck if you are still under warranty, get that truck ripped apart or get Gm to give you a new one. I cant believe that a gm dealer says "we dont know" Under franchise agreement with gm we are not allowed to turn anything away if the vehical is under warranty and the problem the owner is describing is possible or could be happening.
JR-
Renick Cadillac

[Rodeo]

I have a 2007 GM 8500 Series with a 7.8 Isuzu engine, it has loss of power before it goes into Degen Mode, won't even pull the empty truck on a hill,after the Degen light comes on and it goes into the burnout mode it has all kinds of power. It the way the sensors and the pollution control is set up and GM won't reprogram the system. If you could bypass the pollution control system the 7.8 Isuzu Engine is a nice smooth running engine with lots of power for a small engine.

[ISUZU]

Hey i got a 2009 c7500 gmc isuzu with a 7.8 liter isuzu. I'm trying to bypass the egr system due to the system keeps getting clogged up and throwing codes. Once the engine light comes on the cruise control cuts out and the pto won't idle up. The truck is normally used for idling and running the truck hydruralics. Is there any programmer out there that can bypass the egr system and keep the light out?

Thanks mechanic in need of an isuzu pro.

[Spray Foam Tech]

I own a 2008 GMC C7500 which is giving me grief lately. It tries to do a regen but the orange regen light comes on with the green one as well. It stays on for a long time and after it shuts off 5 seconds later its back on, and its making the check engine light come on and also has put me into reduced power mode. I get code P0027 and U0294. Help Pls

[john dear]

new on here, i got me a T 7500 no major issue except a lil electrical problem and some jerkin.

dealer can't find anything wrong with it, i read the gelling effect when in a cold climate country, they say it effect the fuel flow which makes the truck to jerk but once its is warm its all good and so far no complaints except of course the fuel just went up again lol.