12-26-2016 07:52 - edited 12-26-2016 07:57
The nice thing about this website is that you do not have to post multiple questions.
The Owners Zone is the best forum for technical inquiries for your outboard.
The high idle on startup is possibly fuel leaking into the intake manifold either from a pinhole in the lift pump diaphragm or a sticky float valve inside the vapor separator tank. (VST)
When the engine cranks over and will not start up and keep running is often a voltage problem, anywhere from a low-capacity battery, a faulty regulator, or a weak stator. Low or no fuel pressure is also a common cause of hard starting.
The tachometer not reading could be the gauge, the wiring and connections, or a faulty ECU.
You will have to find an experienced technician to troubleshoot your engine to find out why it is not starting easily