hello all. my sierra 2.8 v6 turbo has a starting issue. when left for a few days it takes a while to start the engine seemingly due to fuel issue. when ignition is on there is no power at the pump, but it comes on when starter engaged. it then takes a lot of cranking to actually start the engine. i have tried a lead direct from battery to pump and this still doesn't make a difference. when restarted after an hour or so all seems fine. any ideas would be a great help.