I have a 1995 Dodge Ram Cummins with 280,000 miles on it and when I go to start it after it has been sitting for a while like 5 hours or more it starts really hard like it is really cold out (-23) yet it is 80 degreess. It does this for a couple of seconds and then is really smooth. Any ideas on what this could be would be helpful.

 

MINE WAS DOING THE SAME THING UNTIL I CHANGED THE FUEL FILTER.

 

Check the rubber fuel lines behind the filter.

 

A good chance the return fuel line is going bad. It is allowing air in the line causing a loss of prime.It may be leaking as well.
Rear of the head, drivers side.

 

sounds like a leak in your fuel line

have you changed your return fuel line on your truck yet if not i would change it out

mine did that then started leaking really bad after a couple of days

heres some reading for you
http://www.fostertruck.com/fuel_line.htm

 

It's your fuel line, most likely the return hose that starts behind the fuel filter and runs to the top of the bell housing.
After having the metal lines on top of the bell housing leak on several rigs I now use hose from the fuel filter area all the way back almost to the tank. Abandon the old lines, cut the metal lines by the tank. Makes the job into a ten minute cut and bruise free operation, plus it will be much easier next time around.

 

I just had the fuel return hose replaced July 4 of last year. It started leaking diesel fuel like crazy. is their a chance it could be bad again?

 

If the hose was run of the mill auto parts store gas rated hose or Dodge dealer hose it very well could be leaking again already. Use US Coast Guard approved fire rated diesel hose if you want it to last.

 

I also have noticed a drop in mileage. Usually we get 17-18 mpg or more and now we are lucky to get 15.

 

Could also be a bad / worn out overflow valve.