Last weekend my 03 Yukon Denali XL began starting hard however once started it ran fine while driving. Then while driving down the freeway for about one hour it completely stopped and would not start again. After viewing several of the posts on here I narrowed it down to the fuel pump by turning the key forward and listening for the pump to engage, the pump was not engaging so then I pounded on the bottom of the gas tank and tried again and the truck started, was able to drive the truck home about another hour with no problems. Purchased a genuine AC Delco pump and new fuel filter and installed them, the truck starts but seems to start much harder than it did before the issue began. Once started it seems to run fine, no hesitation issues. Anything else I should be looking into in regards to the hard starts?