I just finished a ~300 mile round trip towing about 4-5k (including trailer) on the way back. The truck felt kind of sluggish. I have towed with the same trailer and a car that was about 500lbs or so lighter than the one I just pulled and I didn't notice it then. The only thing I have done since then is go from 265 BFG Rugged Trails to the 285 Cooper ATRs. Would this make that big of a difference? Going up moderate inclines I had to downshift into 5th, and I don't think I had to do that before. No mods except straight pipe. Air and fuel filters have less than 6k on them. Any ideas? Or was I imagining things?

Thanks,
Nick

 

Check your Fuel Filter. Just because you only have 6,000 on it there is still a possibility that you have a clogged filter. Remember that it only takes one tank of Fuel to ruin one. I had the same problem with my last Cummins. Your air filter may need to be changed also. Last but not least, Fuel Pump may be going

 

I will try the fuel filter, air filter looked pretty clean. I hope not the fuel pump. But the truck seems to run strong without the trailer. But I could be wrong, since I am not driving it as much as I used to. The truck currently has about 56k on it, if that makes a difference.

Thanks,
Nick

 

Something sounds wrong. I pull a 10K# 5-er and have only dropped out of 6th on the interstate twice in 45K miles. Once on I26 near Ashville, NC and on I25 in southern CO. This from a 68 MPH cruise on the cruse control.

Fuel filter would be my first guess also.

JOhn C

 

had the exact same problem,it was a bad rail press. relief valve and a leaking injection pump.replaced the relief valve first and it got alot better but still was not right,then I noticed my cp3 was leaking so I rebuilt it and it runs great again.

 

I would imagine the change in tire size would be noticable, especially towing with 3.73's. If it seems just a bit down on power, I would think that might be it.

Do you have a set of stock tires/wheels that you could slap on for a little test tow?