Got a JD6320, year 2002, with electric fuel pump in tank.Just put in new pump and sender unit(they come together)old pump kept stopping and sender didnt work(bad,rusty ground). The new one stops sometime while key is on, engine not running, while its stopped and key on I have 12 volts at pump leads, and if I hit the bottom of tank with a hammer, the pump starts, than runs a short while than stops again. The tractor runs ok, though, so am wondering if the pump is supposed to cut out after pressure build up ? Still I dont know why after it stops, tapping bottom of tank starts it up again ? Any clues ? This was the first year2002 of this series tractor. We had another 6320, year 2003, that had the electric fuel pump mounted on frame, outside of tank, so am wondering if this set up was faulty and JD made an improvement ??