You say you need to pump the throttle several times & then it will start, when you do this does the fuel pump sound like a strangled cat, if so you are getting air into your fuel system, this could be a chafed pipe or the fuel filter blocked or i have seen the fuel filter head cracked causing the same issue, you may not necessarily see a fuel leak due to it could be on the suction side rather than the pressure side, I would try subbing a fuel filter head first to make sure this is ok, also you can have issue with the fuel injector seals causing the same issue.
Good luck