So it could possibly be the weeping on the injection pump fitting that is causing this.
Now you made me unlazy myself and look it up to be sure, the 9KK were Catabishi, and while they may have the American key switch, they have Mitsubishi wiring, so actually they do have a safety relay in the circuit breaker and relay box along with the starter relay and the glow plug relay. 094-2080: RELAY SAFETY. Not that I'm sure that's the problem, more than likely it's something more simple like the lockout switch or a stuck solenoid.Cat doesn't use a safety relay. The key switch is set up so that you can only hit start position once. If the engine doesn't start then you have to put the switch to the off position and then try to start the engine again from there.
There is a switch on the hydraulic lockout on the left side console. Make sure the lever is all the way in the cut off position before trying to start the engine.
Refer the attached image for the identification of the components.The relay or solonoind I feel the this from is the bottom one that has yellow and red wire in it.