Does my merc outboard 4 stroke fire every time?

Yes, a Mercury 4-stroke outboard engine should fire every time the ignition is engaged, provided it's in good working condition and all systems are functioning correctly. Factors such as fuel supply, battery charge, and proper maintenance can affect its reliability. Regular servicing and checks on components like spark plugs and fuel filters can help ensure consistent firing. If you're experiencing issues, it may be worthwhile to consult a mechanic or refer to the owner’s manual for troubleshooting.