My DK45 has 3 wires that go to the fuel solenoid, Black, Red, and Blue. The Black wire is ground, the Red wire is 12 volts positive anytime the "ign" switch is on. The Blue wire is 12 volts positive for about 3 seconds any time the "ign" switch is turned from off to on, and is powered from one of the three relays located on the fuel tank heat shield.
The Red and Black wires form a circuit which "holds" the solenoid engaged anytime the "ign" is on. When you turn the "ign" to the off position, the circuit is killed, and the solenoid de-energizes allowing the spring loaded rack to move the injector pump pistons to the stop position. This 'Red and Black" circuit is strong enough to hold the solenoid plunger in the "On" position, but not strong enough to move the plunger into position.
When you turn the "ign" switch from the "OFF" position to the "ON" position, a timer circuit energizes a relay, which, in turn energizes the Blue wire, which, along with the Black wire forms a second circuit, which develops a much stronger magnetic field forcing the solenoid plunger into the "RUN" position. This circuit is only active for a few seconds, because it would eventually over heat.
When you say "after a few tries, it fires right up"; Are you turning the "ign" switch "OFF" between tries?? Or are you just going between "start" and "on" with each try?? If you never turn the switch to the "OFF" position between "tries", then your symptoms have me baffled!
If you ARE turning the ign switch OFF between tries, then I would feel confident that your 'gremlin' is an intermittent problem in the "Blue and Black" circuit. From what I have gleaned from reading posts over the years, the overwhelming majority of the times it has been the Relay. A relay is just a set of switch contacts that is operated by an electromagnet. The contacts absolutely can 'sometimes' make the connection, and 'sometimes' NOT make the connection.
It should not be any problem tracing out the circuit using nothing but a test light, or voltmeter.
When (IF) you have the tractor running again, try shutting it off using the lever located just above the "stop solenoid" NOT BY USING THE IGN SWITCH...KEEP THE IGN SWITCH ON! After the engine dies, I would predict the engine will easily re-start (IF you do NOT turn the switch off). If your tractor has a manual transmission, you could also kill the engine by shifting into High range, 4th gear, at idle, then releasing the clutch while holding the brake.
Good Luck!
