Few things are more annoying — and worrying — than a boat engine that just won’t start! Especially if you are new to boating, you may immediately wonder whether your engine has sustained serious damage.
Don’t panic yet, though! Before you start pulling your hair out, take a step back and a deep breath. Then, methodically work your way through a list of possible problems (and solutions).
Whether you’re actively looking to solve a problem with your boat engine right now, or you’re just prepping for future troubleshooting, it might even help to print a list of potential reasons your boat engine won’t start out to keep on board.
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When Your Boat Engine Won’t Crank Or Your Boat Engine Cranks, But Doesn’t Start
Were you just about ready to get your boat started, and looking forward to an exciting day on the water, only to discover that your boat’s outboard engine will not crank at all? Does the engine crank, but excruciatingly slowly? Or does it crank, but fails to start? Trouble getting your boat engine to start is all too common, especially when the boat has been in storage over the winter.
You’ve got a lot to think about — the underlying reasons for your failure to start your boat engine are rather varied. Some are easier to diagnose and deal with than others. Work your way down the list, and see if you can solve the issue!
Are Your Boat’s Safety Features Engaged?
It always pays to cross the simplest problems off your troubleshooting list first if your boat engine won’t start. Nearly all boats are armed with ignition interrupt features and safety lanyard. To start the engine on boats with these features, the safety lanyard (also called a “kill switch”) has to be connected at all times. Any ignition interrupt system should switched on to be able to start the boat. Fixing your problem may be easier than you think!
Are Your Gauges and Lights Working?
Does your boat engine seem to be completely dead? Try to insert the key, switch it to “on”, and observe whether your gauges and lights are working. Is the answer a resounding “no”? Next, go and check your outboard engine’s main fuse. If your gauges and lights are working, however, it’s more likely that your boat simply isn’t in neutral.
Is Your Boat’s Battery Switch Set to “On”?
Does your boat come with a battery switch? That feature has its benefits, as these switches help your marine electrical system last longer and ensure that your battery is fully charged while you are out on your boat. It might just be set to the “off” position, though — in which case your boat’s engine definitely won’t start. Even if you feel silly, just check. You may be off on the water in no time!
Could Your Battery Be Low or Drained?
Here’s another “Captain Obvious” problem, but we want to cross all our Ts, don’t we? In cases where your boat’s engine cranks, but barely, chances are that your battery is simply low, and it needs to be charged before you can start your engine properly. If your marine engine isn’t cranking at all, the battery could also be entirely drained.
Are you not sure about the status of your battery? You can always use a voltometer to check! Boat batteries should be charged 12.6 volts for a complete charge.
Is the Connection Between Your Batteries and the Engine Intact?
If your battery switch is set to “on” and your battery is fully charged, there is one more battery issue to check off your list when your boat engine won’t start — check the connection between your batteries and your boat engine. The connection between your battery and your boat’s outboard engine could be faulty. This could simply be a matter of loose cables, which you can fix easily, but corrosion is another common issue. If your cables are rusty, you will need to have them replaced to get your boat engine to start again.
Could Your Boat’s Fuel Tank Be (Nearly) Empty?
Is your boat engine not starting? An empty tank is another possible cause to eliminate. You know this, of course, but if you were certain that you filled the tank up the last time, you might neglect to check the tank and move straight to more complex possible issues. Always check the tank! In the best case scenario, your tank is just empty, and there are no fuel leaks. Ensuring that you have extra fuel on board always helps boaters deal with this simple but annoying problem.
Are There any Errors in Your Starting Sequence?
Are you trying to operate a new boat, or a boat that you’re not familiar with? If your boat’s engine won’t start, you might not be going about the starting sequence in the right way. Have a glance at your boat’s manual to see whether this could be your problem. Remember, some boats need you to insert the key into the ignition to choke the motor, while other boats require you to pull a manual choke knob out.
Are you getting your starting sequence right, but is it unusually chilly out? You may have to be a little more forceful and patient, but your boat engine should start in the end, unless you have other issues.
Is Your Boat in Neutral? Do You Need to Switch Gears?
Sometimes, all you need to do to get your boat’s engine to start is shifting gears! Most boats with outboard engines have to be in neutral before the engine can be started. If this is your issue, too, your gauges and lights will be fully operational when you try to start the engine. Making sure that your gears are neither in forward nor in reverse, and shifting gears to neutral, may just do the trick and get your boat started.
Is Your Engine Primed Correctly?
The modern outboard engines most boats are equipped with these days run like a charm, but they still have to be primed — that is, air has got to be removed from the fuel system. If your boat engine won’t start, making sure the engine is primed is another item to check off your troubleshooting to-do list.
How do you know if the primer is working? That’s a two-person job. The system isn’t identical for every boat, but many boats have electrical primers. In this case, you can remove one of the fuel hoses that links the primer and the carburetor. Ask someone else to get the key into the ignition, while you keep a close eye on the hose. Catch the fuel that should soon appear into a bucket.
Do you have a pressurized fuel system, instead? The process of making sure your engine is primed is even simpler. Give the primer bulb a few squeeze and see if it becomes hard — meaning the system is correctly pressurized.
If your engine isn’t primed, there could be a leak somewhere along the line, in the fuel lines, filters, or even the engine itself. At this stage, calling a certified boat mechanic is a solid choice.
Are the Fuel Lines Obstructed?
Fuel will not be able to make its way from the tank to the engine if you’ve got a literal kink in the cable. Check your fuel lines for the presence of obstructions, bends, or kinks, and if you do notice that your fuel lines are pinched or otherwise blocked off, have them replaced.
While you’re at it, perform a thorough inspection to make sure that the fuel lines’ couplings haven’t come loose, which happens more often than you think. That, too, would prevent your boat’s engine from starting, but is often easy to fix.
Does Your Boat’s Fuel System Have Any Grit or Water in It?
It is quite possible for grit — sand and salt crystals from sea water — to build up in a boat’s fuel system. That might not cause any issues right away. Over time, however, your boat’s fuel system can become so clogged that your engine won’t start at all.
Sand and salt crystals are heavier than fuel, and will sink to the bottom of the tank. By taking a good look, you’ll be able to see a nasty layer of grit. Water can get into the tank as well, and you’ll be able to spot that quite easily, too.
The solution? Flush your fuel system, install a new fuel filter, and fill your tank back up. Your boat engine will now, hopefully, start without any difficulties.
Inspect Your Boat’s Air Vents and Exhaust: Are There any Blockages?
Checking whether the air vents of your boat’s gas tank are open and free from any kind of obstruction is another important step to take if your boat engine won’t start. Ignition can’t take place without proper ventilation, after all.
Blockages of this kind are especially common after the winter season. Every boater knows that pests pose all sorts of threats while a boat is in storage, and rats and birds can both cause obstructions within air vents and exhaust outlets. You bet that that will definitely stop your boat engine from starting! The good news? Pests are usually easy enough to deal with on your own.
Do Your Boat’s Carburetor Settings Need to Be Adjusted?
Remember to give your boat’s carburetor, which has the job of regulating air and fuel flow, a good look when your boat’s engine fails to start. One common problem lies in faulty carburetor settings, because if the settings are excessively lean, the fuel that can reach your engine will be insufficient and your boat’s engine will not be able to start.
An accumulation of dirt or grime within your boat’s carburetor will, however, lead to a similar situation. In this case, you will have to clean the carburetor and adjust its settings before attempting to start the boat’s engine again.
Do You Need to Have the Started Solenoid Replaced?
Does your engine click or grumble when you turn the key? The issue is likely to lie in the starter solenoid. Yes, you can try using a hammer and giving the starter a gentle nudge, but that’s a bit like taking a painkiller for a toothache, instead of seeing a dentist. You know the drill — get a certified boat mechanic to diagnose and repair the problem, which will probably involve having the starter solenoid replaced.
Inspect Your Boat’s Spark Plugs for Dirt and Damage: Do You Need New Spark Plugs?
If your boat’s outboard engine is painfully slow to crank, taking a good look at the spark plugs is another very good idea. Spark plugs will inevitably grow dirty over time, and they can also become damaged. In both cases, an engine that’s slow to crank will result. Spark plugs that are not gapped properly will lead to delays in getting your boat to start as well.
Having your spark plugs replaced or cleaned is easy enough, and if this was the problem, your boat will instantly gain a significant performance boost.
Check for Poorly Gapped Ignition Points
The next item on your list should be to check whether your ignition points are gapped properly. If they are not, you will have a hard time getting your boat engine to start. You can clean the ignition points yourself, and adjust the gap as needed. If, however, you notice any damage, it’s time to call a mechanic for repairs.
Give Your Boat Engine’s Manual and Auto Choke Linkage a Thorough Look: Is There Any Damage?
Your choke linkage will have likely three positions — off, auto, and manual. If the manual choke linkage has developed bends or dents, even small ones, you could find yourself facing serious challenges as you try to start your boat engine. If you know how, you can fix smaller bends yourself, but if the bends are more pronounced, you will need to call a certified boat engine, who will be able to tell you whether the choke linkage can be repaired or needs to be fixed. An automatic choke linkage may need to be readjusted even if no bends are present.
Is Your Engine Timing Out of Sync?
Improper timing and synchronization often indicate internal damage within the boat engine. A broken flywheel may be to blame in this case, or the flywheel could have become disconnected as a result of other damage within the engine, such as a sheared fastener. In both cases, the crankshaft will fail to spin as you attempt to start your boat engine.
This more serious mechanical challenge requires professional input — your engine will have to be repaired.
Is the Insulation in Your Boat’s Electrical System Worn Out?
Performing regular maintenance is a key part of ensuring that your boat performs reliably, but if you are an avid boater, some degree of wear and tear is inevitable. If your boat engine won’t start, worn out insulation is one of countless possible causes.
If you haven’t found the problem — or at least have a pretty good idea of what may be wrong — yet, definitely inspect your boat’s entire electrical system, focusing on wiring and insulation. Should you spot any loose wires or frayed insulation, you would be advised to have the damage repaired professionally at the earliest opportunity.
What do you do if you spot loose wiring or worn out insulation while you’re already on the water? That’s why you should always carry electrical tape on board! Patch the problem up, and have it seen to as soon as possible .
Got a Two-Stroke Boat Motor? Check Your Reed Valves
Reed valves are, on a two-stroke boat motor, like the intake valves on a four-stroke motor. They regulate air and fuel flow and are placed directly below the boat’s carburetor. There, the reed valves ensure that air and fuel don’t leak out of the engine.
If your reed valves are damaged, the boat engine will be slow to start, and may not start at all. If they are positioned incorrectly, you will have the same problem. How do you diagnose the problem? In some cases, you may be able to see visible chips and cracks. Reed valves with a correct vacuum seal will not let any light through.
Are Your Ignition Coil and Condenser in Good Condition?
The ignition coil stores energy to feed to the spark plugs, while the condenser helps to create a hot spark. These two often-overlooked parts of a boat engine rarely cause problems, but if they have been used a lot and for a long time, the ignition coil and condenser can wear out.
If this is your problem, the boat engine either won’t start at all, or it will start but fail to run smoothly. The coil or condenser may have weakened and cannot store enough energy, and will need to be replaced.
Are You Dealing with Damaged Distributor Caps or Rotors?
Finally, the distributor cap and rotor that feed energy from your ignition coil to the cylinder may have sustained damage. In this case, your boat engine may start, but it’s likely to behave strangely. Replacing these parts is simple enough, but first you have to identify the problem!
What to Do When Your Boat Engine Won’t Start: A Quick Checklist
We have, so far, taken a very thorough look at all the reasons that could cause your boat engine to fail, or to start slowly. If you were looking forward to a nice day out on the water, and planning some serious fishing and relaxation, only to discover that your boat engine won’t start, it is all too easy to panic.
That’s understandable — it is entirely possible, of course, that your boat engine is not starting because of serious engine damage that’s going to be rather costly (not to mention time-consuming) to repair. Remember Occam’s Razor, though; the simplest solution is often the correct one. Before you even consider taking your boat engine apart, check whether the reason your boat engine isn’t starting is something that’s easy to fix.
Believe it or not, these are indeed some of the most common reasons why a boat engine won’t start:
- Your boat’s fuel tank is empty, or nearly empty.
- The fuel tank’s air vent is closed.
- The safety lanyard has become disconnected.
- The boat wasn’t in neutral.
- The battery is low or dead.
- Water or dirt are present in the fuel system, and it needs to be cleaned.
- Your boat’s battery switch is set to the “off” position.
- Checking all of these potential reasons your boat engine will not start can save you a lot of time, money, and stress!
Is your boat engine still not starting? Now you can start looking into more serious issues. They include kinked fuel lines, a problem with the pump primer system, the need for carburetor settings to be adjusted, and problems with engine timing and synchronization.
You may also be looking at a clogged fuel filter, damaged, dirty, or poorly connected spark plugs, poorly gapped, dirty, or broken ignition points, frayed insulation, loose wiring, problems with reed valves, a weak coil or condenser, or broken distributor caps or rotors.
Not every boating enthusiast will need to call a certified boat mechanic to diagnose and repair the problem — spark plugs are, for instance, easy enough to replace, and if you know how to do it on a car, you’ll be able to fix your boat and get the engine to start, too.
Your boat is bound to be one of your most precious possessions, though, so apply common sense. If you are competent at DIY, go right ahead. If you have no idea whether you know what you are doing or not, leave the job of repairing your boat engine to a certified boat mechanic, instead.
