Hi guys, hope someone has some good advice for me... So I bought a duramax about october, to replace the 2000 K3500 6.5TD dually that I've had for a couple years... the old dually always ran ok for me, not great power, and smoked a little under load, I don't think it was making as much boost as it should have been, but always started and drove ok without any issues... so I stopped driving the dually when I got the duramax, and the dually mostly sat after that, except for moving the odd trailer around my business lot, etc... then I put the old girl up for sale before christmas a little, and then a guy on boxing day stopped by my place of business when I was not there and took a quick look around the old girl, and doors were not locked, not sure what all he possibly may have done if anything, then he called and made arrangements for me to meet him the next day so he could see it run and take it for a drive...
so next morning, I threw a charger on it for a bit, just to make sure batteries were 100% but waited for him to show up to do a cold start with him... (always did puff a little cloud upon cold start).. this time though it was very hard to start, and then when it did start, the engine races, and surges from very high down to about normal and then back up again and just keeps surging/screaming away, and smoking like a crack whore, thick black/dark grey ish smoke.... It doesn't seem to be setting an engine light, and throttle pedal input doesn't seem to have any effect or change anything, it just cycles up and down from low to high to low rpm all the while smoking away...
i read somewhere that possible cruise control module failure may cause over fueling, I didn't know what to unplug for cruise module, but I yanked the cruise control fuse out and it didn't seem to make any effect....
I also just after his visit back christmas time, thought since it was cold and I hadn't operated the truck much for a couple months that maybe the diesel was summer fuel and maybe gelling up, so I added some conditioner to the tank, and was able to limp the truck using it's surging around my building and into a small work bay that I have where there is heat, and even after a few days at room temperature it did not make a change....
any suggestions on things to check?? I hate to think that the guy who had come to look at it, and was there the previous day may have sabotaged it in some way, more than likely it was just a coincidence, but the potential is there....
thanks for your time fellas....