i have a 6 spd 2004 3500 dulley four wheel drive truck. When i first bought the truck brand new, 19-21 mpg highway was normal. now it is 13-15 highway and pulling a enclosed 24 ft trailer i get 7-9 mpg. it started when the dealer put a new clutch in it. They took it back and ran it through the computer and they said everything was ckecked out fine. At 70 mph it starts to rumble in the dash but it isn't the barrings, tires, etc. It sounds like the exhaust is plugged???? any sugestions???

thanks big D

 

Have you replaced the fuel filter and air filter lately? Just simple stuff to check first. Not sure what they could of done to create the lower mpg.

 

what did you get pulling the cargo trailer before the new clutch?

 

is it the 305 or the 325 engine?? If its the 325, your cat might be plugged up.

 

exhaust pipe was off turbo when i got my truck back from when they put the clutch on. started it and it was really loud so i saw that the exhaust was off and then i took it back and they put it back on. Could they have left a shop rag on top and it fell in the exhaust when i started it?

 

they could, but your egts would be thru the roof and it would have zero power. how many miles are on your fuel filter?

brett

 

Start w/ basics: fuel filter and driving habits. Have you changed either?