Whether you have a fishing boat with an outboard motor or a speed boat with an inboard motor, you count on the motor to start every time you engage it. Nothing ends a day of fun on the water quicker than hitting the start button or pulling the start cord and hearing your boat engine grind and grind without the slightest indication of starting. A hard starting engine is an indication of a problem that needs to be resolved right away before it leaves you and your passengers stranded on the water.
Like any gas-powered engine, your marine engine needs three things to start and run properly:
- Spark to ignite the air/fuel mixture
If any of these necessary elements aren’t supplied at the proper time and in the proper amount, the engine won’t start.
While most starting issues are related to air or fuel supply and the spark, there are some other problems that can cause your boat engine not to start:
Clogged Flame Arrestor/Air Box
Designed to stop flames from coming in contact with other fuel, flame arrestors help prevent a fire from breaking out. These devices can become clogged with carbon and debris, which will negatively affect the air/fuel mixture, resulting in no start/run rich situations. Remove the clogged flame arrestors and remove the debris using carb cleaner and a wire brush. Air boxes, especially those that are stored in non-marine environments, are susceptible to being clogged with debris such as animal nesting. Make sure the air box is free from debris prior to each startup.
Dirty or Clogged Fuel Filter
The fuel filter keeps dirt in the fuel from getting into the carburetor, and like the air filter, may eventually become clogged and prevent a sufficient amount of fuel from passing into the combustion chamber, preventing your engine from starting.
Faulty Spark Plug
A spark plug fouled by fuel, carbon, dirt or oil on the electrodes may not produce a spark strong enough to ignite the air/fuel mixture and start your engine in older two-stroke engines. Over time, deposits can build up on the spark plug’s center and side electrodes. This changes the gap of the spark plug and can short-circuit the electricity before it reaches the center electrode tip, weakening the spark.
Leaving the radio, lights and pump on while anchored can run down your boat’s battery. If your boat has a two-battery system, forgetting to switch the battery before playing the radio or other accessories can run down both the house battery as well as the starting battery.
Ethanol-based gas can go stale in 30 days or less. Make sure the fuel tank contains fresh fuel, is properly connected and vented and there are no kinks or breaks in the fuel line.
Engine Not Primed
Make sure the engine is primed with fuel and choked properly at start if necessary.
Loose Spark Plug Wires
Improperly connected spark plug wires can make starting your engine difficult. Make certain all spark plug wires are properly connected and free of breaks. Also, check that the distributor cap and rotor are functioning properly.
Problems with Kill Switch
Check that the safety lanyard/kill switch is functioning properly and in the correct position.
Clean flame arrestor/air box.
Replace dirty or clogged fuel filter.
Replace fouled or dirty spark plug.
Switch to house battery when anchored and carry a jump starter.
Replace old gas with fresh gas (properly dispose of old gas).
Replace loose or damaged spark plug wires.
Test the kill switch to ensure its working and in the correct position.
If none of these suggestions resolves your starting issues, then it’s time to call on a professional mechanic who specializes in small engines.
Did You Know…
Q: Why don’t marine engines have air filters
A: Since they operate in a mostly dust-free environment, marine engines typically will not have an air filter. Outboard motors utilize an air box in front of the carburetors to quiet the sound of air intake to the engine. Inboard motors use a flame arrestor on their carburetors to eliminate the possibility of fire and/or bilge explosion.
The content contained in this article is for informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content.
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