2004 GMC Yukon fuel pump replacement

I recently had to replace my fuel pump on my 2004 gmc yukon denali xl my truck was running fine the only reason that it needed to be changed was due to the gas leak which was coming from where the lines connect to the fuel pump I removed the old one there for did everthing I was suppose to and my truck will not start I have then informed the auto store and ordered a new part which they say may just have been defective im hopoin not to run in to this problem with the new part b ut if it occurs what should I do? I have checked some fuses all good there and the gas does come out of where it should under the hood also they checked to see if my car ran with spraying gas into the engine and it stayed running as long as we did that I am under the assumption that the pressure from the pump wasnt where it was suppose to be but if u have any other suggestions they will greatly be appreciated thank you