I have a 2005 6420 that’s been acting up lately. It will fire up and run no issue, every now and then it will just die like it’s lost fuel. Sometimes it will start right up, other times I have to (here is the crazy part) crack the drain on the first filter which starts sucking air and lets the pump suck fuel again and the tractor will start. I’ve had the tank off and cleaned, replaced the line between the top of the tank and first filter, new filters and new fuel pump. Every now and then the tractor will run rough and cracking the filter and letting air in helps. Scratching my head over why adding air is helping!