hard starts
 

need help. 2005 cummins. When i turn the key to "run" i hear the lift pump run for a second or two. Try to start the motor and all it does is crank. tun key back to "run" and the lift pump will run for 4 to 6 minutes. When it does start, a puff of black smoke shoots out of tail pipe. i have a air dog lift pump i installed a year ago but it has been doing this for at least 2 years. comes and goes, at times it will start normal for months at a time. No codes have ever come up as in fuel pressure. when idle the edge programmer shows 6.2-6.7

line leak?