On the 2305 ,It's the fuel solenoid RELAY switch people.. I had the same scam pulled on me.. The dealer would not help me diagnose the problem.. I cracked the lines and only a tiny squirt came through all three during cranking.. I checked the solenoid and it pulled in(momentarily).. I took the pump to a specialized rebuilding shop to the tune of $1250.. Still wouldn't start and same tiny squirt from the lines when testing.. Finally after pestering the dealer he admitted i could remove the solenoid temporarily to see if it fired and whala, it did.. I'm wiling to bet big money the dealer charged you for a pump rebuild and never did one.. He just replaced the solenoid RELAY switch.. Total bait and switch scammer style.. Take it from someone who learned the hard way.. The solenoid has two coils inside it.. One for initial opening and one that holds the pin back while running.. This seems to be a case of planned obsolescence on the part of the john deere design team.. Make the customer think he needs a rebuild and charge for one while only replacing a 40 dollar part..
I never did get a new relay.. Just cut off the pin on the end of my solenoid and added a petcock to my fuel line.. I have to prime it with the little lever on the injector pump but no more starting problem.. Figured i would share this info as i hate seeing others spend big bucks to fix a tiny problem that should NEVER have happened.. Other than this issue the tractor is a great machine and BTW kubotas suck.. Trust me i have years of experience on this issue..
So to diagnose just remove the bolts from the solenoid from the tractor and let solenoid dangle. A tiny bit of oil will spill but nothing major, just don't run that way for long..The injector pump has an oil gallery inside it from the engine oil... If it starts it's the relay.. The pin on the solenoid presses a cutoff lever inside the injector pump.. Okay hope this helps you guys..