All boats require precautionary measures before starting, whether they have been in winter storage or sitting for a time. Inboard engines have more complex systems that the outboard engines, since safety can be more of a factor with larger engines on board the vessel in confined areas. Proper preparations and starting procedures can eliminate permanent damage from a cold start. Inboard engines are more delicate than automobile engines, requiring more frequent inspections.
Pull the engine cover completely off the engine and let it air out. Watch for gasoline fumes that might point to a leaking gas line. Check for gas leaks and tighten any fittings. If equipped with ventilation blowers, turn them on and let them run for several minutes, purging all fumes from the engine area.
Use a voltmeter to check the battery for a full charge. Marine batteries, if unattended for any length of time, can discharge, especially at the ground connections. Clean the battery posts and cable connections with a battery terminal brush
Check the fuel filter. If the craft comes equipped with a water sediment bowl, remove it and empty it completely. Replace the fuel filter if the boat has been stored or winterised. Condensation builds up very quickly in boat fuel lines and filters. Replacing the filter will guarantee that no debris or water exists in the filter elements. Trapped water will cause a no-start condition.
Top off the fuel tank(s). Add a fuel additive that will absorb contaminants and water. Make sure the fuel tank vent cap has no obstructions and has the proper venting. Wipe up any gas spills.
Drain the oil and replace the oil filter if the boat has been sitting for a long time or has been winterised. This will rid the crankcase of any water or fuel that has collected in the engine. You can use an oil evacuation system to remove the oil through the dip stick filler tube, or you might need to unscrew the oil pan drain plug. Drain the old oil into a pan for proper disposal.
Check the level of the out-drive gearbox fluid to make sure it has the proper level. Inspect all the grease fittings on the steering arm, motor pivot points and throttle linkage. The connections should be lubricated and secured, and should move freely.
Top off the radiator on water-cooled engines. The coolant should be clear, with no discolouration or debris. Install the transom drain plug if it has been removed.
Pump the throttle lever two or three times and place it slightly above idle for a start condition. Make certain the boat has been placed in the water so the intake water pump can pick up cooling water. Turn the key and wait until the engine catches and runs. Let the engine run slightly above idle for several minutes, then gradually raise the throttle. If the engine runs smoothly without missing, you can launch.