For some reason when I'm pulling my trailer wich is a 12000 pound 40 foot 5th wheel at about 30 to 35 mph in 3rd gear the truck starts to jerk the rpms and speed don't change but the truck will jerk like its in the wrong gear

 

Sounds like an adjustment to the governor springs is needed.

 

need more fuel

 

Why is it only in 3rd gear doesn't matter if I'm climbin a hill or on flat ground and at around 23 to 2500 rpm. Do I need to tighten or loosen the gov springs

 

do you run in that RPM range in the other gears?It may be a fuel filter.

 

Yes I do. Both filters are new air is clean sediment bowl and screen are clean

 

Maybe if we keep you up at the top of the threads someone might give us some ideas why its doing this.hahaahaa

 

whats egt's look like?

 

I'm with hammer, Sounds like Gov Springs, or turbo surge, which could be incorrect pump tuning, or it could have jumped time. Other symptoms would be more likely than a surge like issue. What transmission?

Feel free to give me a call, I'll be glad to walk you through some diagnoses!

 

Nv4500 egts are around 900 to 1k. If it were the turbo surging id hear it and its just screamin away at around 20 pounds not jumpin at all. I forgot to mention this earlier but if I back off the mat just a bit it stops or if I put it to the grille it stops. What I don't get is it only does it with the one trailer and nothing else I checked the trailer brakes to see if they were surging and they weren't the other thing I thought was my clutch maybe but like I said its just this one trailer