P0628 code
 

Suggestions on P0628 on replacing lift pump or installing in tank pump. What are the pros and cons to replace existing pump by fuel filter or to put it in the tank? Cost and ease to do this what do you think???
Also, should I check relay voltage to see if relay could be the problem? What should the voltage read?
If so where is the relay located on dodge 2004 5.9 L diesel engine?