Hello i have a hitachi ex300lc-3 the batterys have been disconnected for 2 months when i turn key on the throttle defualts to half throttle and will not decrease to idle unless u turn the key off and disconnect the kill switch. Then it will idle fine. Trying to figure out if i have to recalibrate the throttle motor with doctor zx or if maybe throttle motor has given up the ghost from sitting.
It likely that you just need to re learn the throttle motor. With key on, push "P" max power mode switch. Wait 4-5 seconds for the EC motor to move linkage to fast idle stop. Turn key off and wait for the battery relay to shut off, then start the engine.
That doesnt seem to fix the problem
I've got a 300-3 that I use in my mining operation. It sits with the batteries disconnected for 5 months over winter. Never had a problem when I reconnect the batteries in the Spring and fire it up. So I don't think it is related to having batteries disconnected. I'd just run it a while and see if it fixes itself.