When your outboard won’t start, there’s a good chance you can fix it in a few minutes with no tools at all. I’ve been running outboards for over 50 years, including 17 years of full-time life aboard, and about 95% of starting problems come from the same short list of causes. Most take less than a minute to check.
It doesn’t matter what brand you have, or whether it’s a 2-stroke or 4-stroke. The checklist is the same.
Only one check below requires a tool, a small flat-blade screwdriver. A roll of Rescue Tape (Amazon) is also worth keeping aboard. It can patch a cracked fuel line well enough to get you home.
First: Don’t Drift Into Trouble
Before you start troubleshooting, make sure you’re safe. If you’re not tied to a dock, anchored, or tied to another boat that is, deal with that first. Row or paddle to safety, tie on, or drop anchor.
And if you smell gas, put out any cigarettes or open flames right now, before you touch anything else.
Always carry basic safety gear on the water. Here’s what I keep aboard.
Five Clues That Tell You What’s Wrong
Take 10 seconds before you touch anything. Notice what’s happening, then jump to the right section.
- It doesn’t sound like it’s even trying to start
- It almost starts but won’t catch
- You smell gas
- You’re using an external fuel tank with a hose
- It starts but dies when you put it into gear
It Doesn’t Sound Like It’s Trying to Start
No sign of life at all? Check these in order. These are the most common “nothing happens” causes.
1. Kill Switch (Deadman Cord)
Make sure the kill cord is attached properly to the motor. Don’t just glance at it. If it’s even slightly out of place, the motor won’t start. Unclip it and clip it back on firmly.
In my experience, this is the single most common reason an outboard won’t start. It’s also easy to knock loose when boarding or shifting around. Once you’ve ruled it out as the culprit, it’s worth reading how to wear the lanyard so it stays clipped in underway without accidentally killing the motor every time you reach for something.
2. Out of Gas?
Yes, really. Check the fuel level. Easy to miss on outboards with a small built-in tank, common on motors around 6 HP and under.
If you have an external tank, there may be a little fuel left but not enough for the pickup tube to reach. Try tilting the tank so the fuel pools at the end where the hose connects. Anything works — prop it on a life jacket, a bag, even your toes. Sometimes that’s all it takes to get home.
3. Tank Selector Switch
Some motors can run off either an internal or external tank, with a selector switch on the front of the motor. Make sure it’s set to the tank you’re actually using. It’s easy to bump when lifting, tilting, or moving the motor.
4. In Neutral?
Many outboards won’t start in gear. Make sure you’re in neutral. It’s easy to accidentally nudge the shifter into forward or reverse without noticing.
5. Battery (Electric Start Motors)
If you have an electric-start motor, the battery may be dead. Many smaller outboards also have a pull start. If yours does, try it manually. Even if you can’t pull-start it yourself, a nearby boater might be able to help. Know where the cord is before you need it.
It Almost Starts But Won’t Catch
Trying but not quite firing? Start here, but also check the I Smell Gas section if there’s any fuel odor.
1. Choke
Try starting it both with and without the choke, even if you think you know the right setting. Sometimes that’s the entire difference between “almost” and “running.”
2. Throttle
Adjust the throttle position slightly. Not wide open, just a little more or a little less than your usual spot. Sometimes that small change is all it takes.
I Smell Gas
A fuel smell means one of two things: the engine is flooded, or there’s a leak in the fuel system. Work through these in order.
1. Flooded Engine
Flooded means too much fuel got into the engine. It does not mean you dropped it in the water — that’s a different problem entirely. Flooding is the most common cause of a fuel smell, especially after several failed start attempts.
Don’t squeeze the bulb. Then try one of these:
Option 1: Wait 10 minutes. The excess fuel will evaporate on its own. This often works without any further steps, and it’s always the safe choice.
Option 2: Clear-flood start. This only works if your motor lets you be in neutral with the throttle wide open at the same time. Many tiller models and some other outboards have a single control that combines throttle and gear shift with no way to separate them. Some have a trick to get to neutral independently first — on ours, you pulled the shifter out. If you’re not sure whether your motor can do this safely, use Option 1 instead. Attempting a clear-flood start when the throttle and gear are linked will send the boat lurching forward unexpectedly.
If you’re confident you can be in neutral with the throttle open:
- No choke
- Throttle all the way open
- Pull-start 2 to 3 times (sometimes a few more)
If it doesn’t start after about 6 pulls, stop and wait 10 minutes. If it fires and then dies, restart using your normal cold-start procedure.
2. Fuel Leak (External Tank Only)
If you have an external fuel tank and the smell was there before you started attempting to start the motor, or if you can see or feel fuel on the hose or fittings, you likely have a leak rather than a flooded engine.
Run your hand along the full length of the fuel hose. Look for a cracked, cut, or nicked section, or a loose clamp at either fitting.
If it’s a loose clamp and you have a screwdriver, tighten it. If it’s a crack or nick in the hose, wrap it tightly with Rescue Tape (Amazon) as a temporary get-home fix. Keep your speed down so the engine isn’t demanding much fuel, then replace the hose as soon as you can. One crack usually means the rest of the hose isn’t far behind.
You’re Using an External Fuel Tank
Most starting problems on motors with an external tank happen somewhere between the tank and the engine. Do a quick visual check from tank to motor, then run your hand along the full length of the hose. A lot of problems become obvious just from doing that.
1. Tank Vent Open?
Make sure the vent on the fuel tank cap is open. If it’s closed, air can’t replace the fuel being drawn out and flow stops. If the vent is open but the tank looks collapsed or sucked in, the vent may be clogged. Crack the gas cap to let air in. That will usually get you home, unless it’s rough enough that water could splash into the tank.
2. Fuel Line Connected — Really Connected?
Lines can look connected when they’re not fully snapped in. Disconnect and reconnect at both ends (tank and motor), then tug gently on each to confirm they’re clipped in.
3. Fuel Line Kinked or Pinched?
Look for a kink like you’d find in a garden hose. Common causes:
- Hose pinned under the tank
- Hose squeezed between the tank and the hull
- Someone stepping on it
- Gear sitting on top of it
Also check right where the hose enters the motor. We once had a hose bent so sharply at that point it was essentially crimped shut.
4. Squeeze Bulb Firm?
Squeeze the bulb until it feels firm, but don’t keep squeezing beyond that. Too much and you’ll flood the engine.
If the bulb never firms up, you may have a closed tank vent, a kink or blockage, or a cracked hose pulling in air.
If you squeeze the bulb and smell gas, stop squeezing and go to the Fuel Leak section above.
5. Blocked Fuel Hose (Delamination)?
Some hoses have an inner liner that can break loose and wad up inside, blocking fuel flow with no visible sign on the outside. To test: disconnect the hose at the motor, press the ball valve in the hose fitting with a small flat-blade screwdriver, and pump the bulb to see if fuel flows out strongly.
If it’s blocked, the real fix is a new hose. As a temporary workaround, keep your speed down and pump the bulb frequently to push fuel past the blockage and keep the engine running. The slower the engine runs, the less fuel it needs. Pump just enough to keep it going — over-pumping risks flooding the engine.
It Starts But Dies When You Put It Into Gear
This is the classic sign that something is wrapped around the prop. Turn the motor off, tilt it up, and check carefully. It’s usually a line, but I’ve pulled all kinds of things out of there over the years. Remove everything you find before you try again.
Bottom Line
When your outboard won’t start, don’t just keep pulling until you’re exhausted or run the battery dead. Take 10 seconds, look for the clues, and work through the likely causes in order. Most starting problems are simple fixes. And if it turns out you do need a mechanic, you’ll be glad you checked the basics first. A fellow cruiser once paid a mechanic his full one-hour minimum only to find out the tank selector switch was in the wrong position. Don’t be that story.
The Next Time This Happens, You’ll Want This in Your Hand
Got your motor running now? Super! But the next time it quits, you may not have your phone or be able to find this page. That’s exactly why I put together Outboard Troubleshooting for Beginners: a simple step-by-step checklist printed on waterproof, fuel-proof paper that lives in the boat and works when things are wet and messy. Also available on Amazon. And getting home is usually easier than it feels in the moment.
Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
Ernie Lorimer says
My Yamaha 9.9s typically need the throttle to be goosed a few times for a cold start. They have an accelerator pump at the bottom of the carb that sprays a little gas into the throat when the throttle is advanced, to help it come up to speed before there is enough air flow to draw gas at higher rpms.
Goosing it a few times sprays some gas into the throat that helps it start, and it is necessary almost all the time.
Bruce Stewart says
Excellent article Caroline. Thanks.
Captain Mark Nine Lives says
“Flooded refers to flooding the motor with fuel, not having dropped it in the water (that takes a totally different and much more “mechanic”-type solution).”
Actually all you need is to be prepared because at some point you will do this. The secret to rescuing your motor is speed and following a couple of simple steps. Get the motor out of the water and quickly follow these steps.
1. Remove the spark plug
2. Pull the starter rope through until all the water has been pumped out of the cylinder.
3. Spray a ton of WD40 or the like into the spark plug hole.
4. Pull the starter rope through several times.
5. Spray a lot of WD40 in again and quickly put the spark plug back in and connect the spark plug wire.
6. Start the engine and run it for a while.
I’ve never had this fail to work and never had any engine issues after,
Carolyn Shearlock says
When it’s gone into salt water, the motor has to be flushed with considerable amounts of fresh water, too. For a 4-stroke, several oil changes. If the gas tank went in the water, get fresh gas before even trying to start it as the gas will have water in it.
Another key is not pulling it out of the water until you have all the tools assembled. Once you get it out of the water, work quickly. It’s usually best to replace the spark plug, particularly in salt water.
And as I said, doing this requires a certain amount of “mechanic-y” skills, which was outside the scope of a 101 article. But yes, good to know how to do.
Rod says
If its flooded with salty , its best to soak it in fresh and agitate it. The salt residue is the cause of damage and will reappear later even months. Corrosion will eat away at electrcal items and connections. Remove flywheel, if you can and wash out electrics and dry.
Gary says
Kill switch can fail, you can disconnet it, and motor will start. Use this trick if you forget the laynard. A good reason to lock your dink
Carolyn Shearlock says
Yes, you can disconnect it if you know what you’re doing. A bit beyond the scope of this post, which is simple things to check.
Craig Newton says
Love your articles Carolyn.
Carolyn Shearlock says
Thank you!
Rob says
I have a 1988 45hp Mariner engine runs with the ear muffs on but as soon as the boat gets put I to water it won’t start. Take it out crank it with the muffs on it starts after a couple cranks. Carbs have been done fuel pump duel lines stater and foils new plugs and wires. Compression is good . Only won’t start when the lower section of motor is in the water. Very frustrated any hell would be appreciated,
Carolyn Shearlock says
Boy, I’m not a mechanic and don’t have an answer for you. One thought is whether there is something with the cooling water circuit, since that seems to be the difference.
Jason says
Did you ever find out what the problem was? Mine is doing same thing
Sammy says
I just had same issue with my 87 evinrude , beat me down for 2 months finally took to a mechanic and it was a $6 piece ,a sheared fly wheel key I’d try that . Granted the flywheel puller is a little pricey but it’s worth a shot
Goldie says
Rob, did you find the problem, because my has the same problem. I have a 50 Tohatsu and it’s got same problem. It’s not overheating it just want crank when you launch t. But with ear muffs on land it will crank and run great.
Garry says
Most outboard vent the exhaust below waterline it be restricted.
Jim says
I have a force forty outboard engine. It starts sometimes and then dies after about 5 minutes. Try to start will not work.
Carolyn Shearlock says
Hi Jim! If the simple solutions listed here don’t help, you probably need to talk to a mechanic.
Carla says
Great article Caroline. One other thing to check in the top four. Many outboards will not start in gear. Don’t ask how I know, I wouldn’t want to embarrass someone. Just check to make sure it’s in neutral and try again.
Carolyn Shearlock says
Another good point! Don’t know how I missed including that. I’m going to add it now.
Hugo Sanchez says
Hi Carolyn – Hope all is well! I have a 88 Bayliner Capri that will only start with the choke button being pressed and held there. What do you think is my problem? I just bought the boat and the first two times I took it out everything worked like a charm. But now, it will only start with the choke button being held in. Do you have any recommendations as to what the problem is?
Thank you so much!
Carolyn Shearlock says
First thing to try would be cleaning the carb, particularly if it only runs if you continue to press the choke. Sometimes you have to clean the carb a couple of times before it’s sufficiently clean. If that does not do the trick, it’s time to call in a mechanic.
Dean says
i have a f25elh mercury four stroke it will run fine and get you as far as you want to go but when you shut it off it will not start back up. Then when you get home it will fire right up and run fine.
Carolyn Shearlock says
That’s beyond the scope of this article. You’ll want to research carburetor troubleshooting.
William Serdynski says
Four stroke engines that start up when cold but won’t when hot usually have valve problems. As the engine warms up, the valves expand and don’t seat as well causing a loss of compression. As long as the engine is running, it usually keeps running. When it cools down, it will start again. A valve job is needed. You will be amazed how quickly engines start with a fresh valve job.
Ken Humphries says
I have a Mercury 2016 60hp 4 stroke motor. It started up and ran just fine until the foot of the engine hit a stump going pretty slow but it knocked the engine off and couldn’t start it up again, it wouldn’t even turn over. Could that bump cause a safety switch to stop engine or cause the timing to get knocked out of line? Help!
Carolyn Shearlock says
That’s going to require more of a mechanic. Good luck!
Ken Humphries says
Thank you, I was afraid of that.
Duncan says
I have a 2001 tracker targa with an internal fuel tank. My issue is, I hook up my 60hp Mercury to an external tank runs like a champ. Soon as I plug it into the internal tank. Won’t turn over. I have a new supply fuel line, checked tightness and sprayed for leaks no problem. Took the fuel siphon valve and fuel withdrawal stem out perfect no blockage. Brand new non ethanol gas with appropriate sea foam additive into it. It is roughly a 20 gallon tank.
I had the boat running at 3000 rpms like two weeks ago.
Carolyn Shearlock says
My first thought is that air is getting into the fuel line (cracked line, fitting or pickup) on the internal tank to motor. A crack that lets air in won’t show as a leak on the suction side.
Rod says
The engine may be too low in water creating back pressure through exhaust
Other thing you may try is to remove plugs taking care with fuel and crank over to see if you’re getting water ingesting to cylinder you may see moisture on plugs or head. Depending on age of engine
Paul St-onge says
40hp mercury Efi starts and stops right away then won’t start for about 10 minute
David Rosenbaum says
I have a new 6hp 4-stroke Tohatsu that I started today for the first time. ( Started on the 2nd pull )After letting it idle for 12 minutes, I shut it off.
After a couple of hours I tried to to start it again and nothing: doesn’t start or even sound like it might. Ideas?
( Prior to the first start, I followed the manual: added oil and pulled starter cable a few times with lanyard detached to circulate oil prior to starting; added fuel to internal tank [non-ethanol with StaBil 360], left vent on cap ‘open’, replaced safety lanyard; motor on outboard stand and 30-gal rubbish bin filled with water to 4” above anti-cavitation plate. Started on second pull; idled smoothly. I also shifted to fwd for a minute or two, then back to neutral. After 10 mins, I stopped it by pressing kill switch.)
Carolyn Shearlock says
Most likely the kill cord got slightly out of place. Remove it and reinstall it, then try again.
David R says
Dear Carolyn,
Thank-you for your suggestion. (And I’m happy to have discovered TheBoatGalley! )
One of the service people where I bought it, Cumberland Watersports (Online Outboards), said that it was likely overfilled with oil (!) and suggested that I drain it and refill with 12-13 oz even though it would read a bit low on the dipstick. I did that and it started right up! So a little Tohatsu peculiarity…
Micheal hill says
I have a 35 hp mercury. I hit a stump and now all it will do is pop and try to run, but will not start. It acts like it’s out of time. But shear key is good. Can anyone help me?
Todd Chiusano says
I have an 07 Honda 90 . It will not start unless I shift from forward to reverse a few times first. Are there contacts somewhere I can check or clean? Or could it be something else ?