Here's How to Diagnose a Boat That Won't Start

"functionoverfashion" (functionoverfashion) 07/16/2015 at 16:23 • Filed to: boatlopnik, boats, how-to

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In response to the !!!error: Indecipherable SUB-paragraph formatting!!! , I thought I’d write up something on boats, because “darling it’s better, down where it’s wetter,” !!!error: Indecipherable SUB-paragraph formatting!!! . I worked at a marina on a lake for a number of years and learned a lot. Now that I’m on to other things, I thought I’d share some of that knowledge before it all escapes my brain.

Obviously the same principles of air, fuel, spark, compression apply for these engines so I won’t necessarily talk about doing a compression test or that type of thing. My focus is on the unique features found in boats that are the common sources of a “no-start.” We dealt primarily in small runabouts, which means mostly outboard, I/O, or inboard (including v-drive) boats under 25 feet. When we would get a phone call at the marina, “My boat won’t start...” here’s what we’d typically say:

Is there any power at all? Like, when you turn the key, do the gauges move? Is there any audible beep or anything? I realize this isn’t unique to boats, but the behavior is - boating is more like tailgating than running errands. Most of the time your car is off, you’re not in it. If you leave the lights on accidentally, many modern cars will shut them off eventually. Most boats are not smart enough to shut off accessories to save the battery. Also, people love to crank music at their favorite swim spot, but guess what? That runs on the starting battery. I will mention that a lot of boats with bigger factory sound systems and lots of accessories will have a dedicated “house” battery like larger boats would have, for this exact purpose. I put a second battery and a switch in !!!error: Indecipherable SUB-paragraph formatting!!! and have had exactly zero dead-battery-stranded situations in 10 years. On to the boat-specific equipment...

Check the safety lanyard. The what? This is a little (typically red) cord that you’re supposed to clip to yourself so that if you (the driver) fall out of the boat, it will shut off. Some boats will crank but not fire, others will not get any power at all. Some even use it as the “key” like many jetskis. But bigger boats still have them even if there’s little to no chance of being thrown out of the boat, and no one ever clips them to anything, so they’re largely forgotten. Until you accidentally bump it while sitting around enjoying a beverage, then try to start the boat.

Is the boat in neutral? Check again. Make sure the throttle/shifter lever is in the middle. Okay, now wiggle it back and forth while turning the key to see if it’s just a crappy neutral safety switch or out of alignment. Being out of neutral usually keeps the starter from cranking at all, like a clutch lockout on a car. Some older (like, 1960’s) inboards have a little green “neutral” light like a motorcycle. Brilliant!

How much gas do you have? Are you sure ? Boat gas gauges are notoriously unreliable. Outboard fuel tanks have little sight gauges that usually break or are faded beyond recognition by the sun after about 2 years if they’re out in the open. A lot of people don’t realize their boat has two tanks. But it says full! Can you lift it? Is it heavy? Is the switch pointed to that tank? Or is there a hose attached? Maybe you need to manually switch the hose, or flip a lever or switch somewhere.

Is it flooded? Have you been cranking it and pumping the throttle vigorously for the last 5 minutes like you’re trying to... yeah. Mmm? Many marine engines still have carburetors, and people are largely unfamiliar with such witchcraft nowadays. Try cranking it with the throttle wide open (usually have to explain what that means) and see if it will fire. Outboard? Stop squeezing that primer ball, it’s not helping. Or try waiting about 15 minutes before trying again. Crack another beer, try again when you finish. The beer, that is.

At this point, we would get into specifics about things like, maybe they’ve got a battery switch to try, or a breaker/fuse that’s blown, or maybe the ignition key cylinder is physically spinning in the dash (these things come loose more often than you’d think)... It was amazing how often you could solve a no-start over the phone.

If we couldn’t figure it out, we’d have to send someone out with the appropriate tools to get them going. They say the battery isn’t dead? Bring a jumper pack anyway. It has plenty of fuel? Bring gas anyway. And much of the time when we sent someone out, the boat could be started and driven back after a jump start, re-fuel, or just the touch of a technician instead of Joey Bagodonuts behind the wheel.

Pictured: Six boats, six different methods of propulsion - inboard, outboard, I/O, water cooled, air cooled, carbureted, EFI, 1 cyl, 3 cyl, 4, 6, 8 cyl. Oh and sail power.

One other common malady was, “It starts and idles fine, I can rev it up in neutral, but when I put it in gear it dies right away.” This was most often solved by asking the person, “Do you have any dock lines hanging overboard? Might one of them be wrapped around your prop?”

Following the diagnostic trail of the technicians was my favorite part of working at the marina, since boats are so widely varied. There are so many different types of engines and controls, and so many different issues plaguing these floating money pits. And people who are otherwise perfectly intelligent often know nothing about their boat. We’d be explaining simple concepts to people who ran multi-million or -billion dollar corporations. Federal Judges. Doctors and lawyers. And that’s what makes boats so great, they make you feel like a kid again, just not always in a good way. But like anything, it pays to be familiar with your equipment ; it might just save you an embarrassing phone call or service call when you’d rather be enjoying yourself.

Pictured: That’s not gone well. Towing in a ~$170k wooden boat with the rudder sheared off. Powered by 8.1 liters /425hp of futility without that rudder.

Bon Voyage!

f86sabre > functionoverfashion 08/03/2015 at 08:13

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We were using a family member’s ski boat last month and it wouldn’t start. Had a Mercury 110 outboard on it. The starter would spin, but the motor would not turn over. Poked at it for a while, changed batteries, checked cables and all that. As a last gasp I whacked the starter with a wrench and it worked...for a while.

Echo51 > functionoverfashion 08/03/2015 at 08:21

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No pulling it up to speed and dumping the clutch incase the starter refuses to crank? #How2Boat

JR1 > functionoverfashion 08/03/2015 at 08:21

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Pictured: That’s not gone well. Towing in a ~$170k wooden boat with the rudder sheared off. Powered by 8.1 liters /425hp of futility without that rudder.

Good Lord! That's how much wooden boats cost?! Looks like I'll never be buying one

kanadanmajava1 > Echo51 08/03/2015 at 08:49

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Remember to use a high gear when you are trying this.

functionoverfashion > JR1 08/03/2015 at 09:01

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Well, no, not exactly. If you want a decent running wooden boat that looks good and doesn’t need major work, you could get one in the $15k range, much less and it will probably need some work. Not that different from, say, a Porsche 911. A cheap one is a bad idea or a major project. But you can spend a crazy amount on a new one if you really want to. This one had, for example, bow thrusters. Things like that can drive up the cost in a hurry.

Echo51 > kanadanmajava1 08/03/2015 at 09:06

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Also do it on stable, firm water so you don’t just lock up the propeller.

You can tell a Finn but you can't tell him much > functionoverfashion 08/03/2015 at 10:44

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Nice write up. I’ve got a 96 Ski Nautique and had a hell of a time diagnosing a sometimes no start, sometimes start fine and run fine and then die and not restart issue. Turns out some of the ignition circuitry is fed by a dedicated line from the battery with a 50 amp inline fuse. The housing had leaked and corroded the connections on the ends. Sometimes it would make good enough contact to be fine, sometimes it wouldn’t. After many hours of tracing and checking we figured that out. Cleaned up the fuse housing and fuse and put some dielectric grease in there and its been fine since. I do carry a spare fuse holder and fuse now just in case. And a crimping tool so I can install the fuse holder.

functionoverfashion > You can tell a Finn but you can't tell him much 08/03/2015 at 10:57

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Ah yes... I love ski boats and have spent a lot of time in them, working on them, etc.

If I were you I’d put a breaker in place of that fuse. Any chance I have, I replace a fuse holder with a breaker. No more carrying spare fuses!

CB > functionoverfashion 05/21/2016 at 16:38

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A bit of a necro, but here’s what we had to do with my dad’s boat (80's Whaler with a 175 hp Johnson on the back): keep trying to crank it for half an hour. Miraculously get it to start. Untie as fast as possible and gun it, as it’ll stall the moment you leave it in neutral for 30 seconds.

Every. Fucking. Time.

Turbineguy: Nom de Zoom > functionoverfashion 05/21/2016 at 18:03

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The ingition interrupter on the shift linkage (Mercruiser I/O) tormented me on my first boat, until one of the marina techs diagnosed the intermittent problem.

functionoverfashion > Echo51 05/22/2016 at 19:16

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How’s this for a late reply? This was pulled into my view again recently and I never saw your comment. This actually is possible with some boats!

functionoverfashion > Turbineguy: Nom de Zoom 05/22/2016 at 19:17

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Intermittent electrical issues, my favorite!

AntiSpeed > functionoverfashion 05/28/2016 at 17:45

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Is there a name for those fancy wooden speedboats?

functionoverfashion > AntiSpeed 05/29/2016 at 10:21

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The little one at the top is a kit-built boat by a defunct company called James Craft. The big one I’m towing is a Grand Craft, a company started by descendants of Chris Smith of the most common wooden runabout, the Chris Craft. Thete are many others though, like Century, PennYan, Shepherd, Dodge....

WhiskeyGolf > functionoverfashion 05/29/2016 at 15:13

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Great photos where are they from? Having a boat stored and serviced properly means that our family’s runabout has never been anything but reliable. It sure beats the 1980s era Johnson we had before.

functionoverfashion > WhiskeyGolf 05/29/2016 at 21:38

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Squam Lake, NH. And thanks! Love it here...

Drakkon- Most Glorious and Upright Person of Genius > functionoverfashion 05/30/2016 at 17:21

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I have inherited my family’s 1986 Celebrity runabout. It’s in fine shape but of course I would like a newer one, but I know exactly what headaches it has and what it takes to overcome them.

functionoverfashion > Drakkon- Most Glorious and Upright Person of Genius 05/31/2016 at 09:17

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Older, well-maintained boats are underappreciated. People see a shiny new object but guess what? Those are expensive too, AND require similar levels of maintenance. Maybe fewer broken things, but spring prep and winterization are exactly the same.

The biggest thing with older boats, like pre-1995 as a general rule, is the use of wood in the stringers, floor and transom. Though it is encased in fiberglass, the wood will eventually rot and the fiberglass alone isn’t enough for structure. And replacing any of that wood quickly gets into the thousands, or DIY which is STILL expensive and difficult and very time-intensive.

Cobalt 232 > functionoverfashion 08/17/2016 at 04:39

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I’m on vacation with my 1999 Cobalt 232 that won’t turn over. I get the audible beep. the dash lights come on and I can put the drive up or down but she will not crank. Dead silence. We have run the boat the last four days without any issue and then all the sudden she won’t start. I have checked the kill switch, she is in neutral and even put a new battery in. Any idea what could be the issue?

functionoverfashion > Cobalt 232 08/17/2016 at 06:41

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Can you access the back of the ignition switch? Is it a standard key or some kind of keypad?

functionoverfashion > Cobalt 232 08/17/2016 at 08:28

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That also sounds like a start solenoid that quit. That can happen any time, unfortunately. Can you access the starter easily? Maybe take some pictures of it? I’m not sure if the solenoid would be right on the starter or just nearby...

Sam > functionoverfashion 08/18/2016 at 12:44

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We bought a 1990 Bayliner Capri (3.0 Mercruisr) a little over a month ago. Replaced the carb, starter and lower stern drive. We also changed the oil (not synthetic) and it has fresh gas. It started right up in the driveway, but when we got it to the lake, it wouldn’t start. We’ve replaced the spark plugs and points (yes, we checked the kill switch and neutral). It’s getting spark and gas, but it just won’t turn over. On the way to the lake, we hit a rather large dip and the boat bounced pretty hard on the trailer. Could it have knocked something loose? We’ve been working on it almost daily for 2 weeks! We’re at a loss and I’m afraid it’s getting to the point of no return, if you know what I mean. Any insight would be greatly appreciated!

Chadd weber > functionoverfashion 08/28/2016 at 18:35

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I have a 1992 four Winns Horizon 180 with a 5.0 OMC Cobra and when we try to start it it will not start it try to turn over but won’t and we just had the lower gears replaced and the gas cap and line replaced. Do you have any possible causes.

Sevas13tra > functionoverfashion 02/14/2017 at 13:02

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I was just stranded, engines wouldn’t start...your article saved my butt!! Who would have thought about starting with the throttle open like that. Many Many thanks from me and my family!!

functionoverfashion > Sevas13tra 02/14/2017 at 13:17

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Haha! Wow, that’s awesome. I’m glad I could help! Basically, if an engine is flooded, opening the throttle all the way allows the most air possible into the mix, and that can (sometimes) overcome the otherwise too-rich mixture that’s in there. Otherwise, waiting about 10-15 minutes without touching anything can allow a flooding condition to clear out, which may be necessary if your battery is weak from attempting to start it too much already.

Hannah > functionoverfashion 05/25/2017 at 11:19

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So yesterday we was fishing and headed in for the night and hit a floating log or something in a 2016 triton and you could immediately feel the loss of power. After shutting off the motor to check for damages and after checking it and looking fine we tried to crank it and it wouldn’t turn over sense then. Any suggestions? Kill switch is on and in neutral.

functionoverfashion > Hannah 05/25/2017 at 11:52

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You have to have knocked something critical loose. How fast were you going? What engine is this exactly? The starter engages and turns the engine over, but it won’t fire and run on its own, right?

A fuel line could have come loose where it connects to the engine; a plug wire could have maybe come loose, although that’s less likely. A wire harness could have come loose, although those are usually quite secure. Those are my initial thoughts.

Hannah > functionoverfashion 05/25/2017 at 13:05

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We where going about 30mph with a 200 motor. It tries to crank but won’t turnover and run like it should. I thought we smelt gas when we was checking it but can’t be sure.

boaty > functionoverfashion 06/12/2017 at 22:09

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i have a problem with this tripping when i put 3/4 throttle or full throttle after running for couple minutes. any idea where to start looking for the problem?

functionoverfashion > boaty 06/12/2017 at 23:25

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Could be a loose or corroded wire somewhere on the ignition circuit or on the switch itself. Also that breaker looks like it’s been replaced. Is it original? If not, are you certain it’s the right amperage breaker?

boaty > functionoverfashion 06/13/2017 at 16:51

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we just bought the boat and this was the second day of us having it out. It ran great all day until we started heading back in. Thanks, i’ll start by checking the wires.

Robert > functionoverfashion 06/17/2017 at 20:02

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We have a 18ft havorcraft boat that haves a car motor in it it’s a 3.0 lite Amc, it’s a I/O as well. We have tryed everything you have said to try to get our boat to fire up but nothing is working but the key will turn over and the lights will come on. We have change the core three times now and it still won’t get any fire to it. We ran it for a month and then we sat it up for a month as well now we have this problem. Can please anyone help us we are at our ends with the boat. Robert 504-312-8512 thanks alot

Thebrokeboater > functionoverfashion 07/28/2017 at 13:47

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I’ve got a one that 2 separate shops have thrown the towel in ON. It is a 2006 Volvo Penta Gi-F

The coil will fire only 3-4 times while cranking and stop no matter how long you crank. If you stop cranking and try again same thing 3-4 times then stop. If I unplug the camshaft position sensor the coil will fire consistently. When i pull up the codes the only code that comes up is 0336 Crank Synch Noise. I removed the entire harness and untaped it exposing all wires to verify nothing was shorting. All those results were good.

Boat has a brand new engine, ECM, Fuel pump, batteries, rotor, Cap, crank shaft position sensor, camshaft position sensor, coil, ignition module, plugs.

Summer is nearing an end and I have still not got to bring boat out this year. Any help or ideas would be greatly appreciated!!

functionoverfashion > Thebrokeboater 07/28/2017 at 14:02

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Let’s back up a minute, why does the boat have a brand new engine? Who did the work?

I know it sounds dumb, but did you bypass safety features (temporarily) like the safety lanyard, neutral safety switch just to eliminate them as possible issues?

Rhutson > functionoverfashion 07/28/2017 at 21:50

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I have a 1995 Mb Sports boat. I have an upgraded sound system and an extra battery. Boat has been running great. I was cruising accross the lake and a buzzing sound pierces through the speakers. I put the boat in natural and turn the stereo on and off. The buzzing sound still continued so I turned the boat all the way off. Now the boat will not start. I am not getting any power to the dash, ignition, or stereo. Tried to by pass the starter and do a hot start and it just would turn and turn... any help would be appreciated

functionoverfashion > Rhutson 07/30/2017 at 21:13

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I’d start by checking all your battery connections, does one battery run the stereo or do they both run everything?

kiwibbq > functionoverfashion 04/02/2018 at 05:36

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hi I have just bought a boat with a 85 mercury on it. it has been sitting for the last 3 years but I was told it ran good. I think its from the 1980s, 4 cylinder 2 stroke. I cleaned up as much as I could without pulling anything apart got some new fuel and gave it a go. with a little squirt of engine start it fired up and ran really nice for about 20 secs then died and would not start again. after leaving for a couple of days did the same thing and the same thing happened. there is water coming from the tell tale the fuel mix is bang on no smoke or anything but runs sweet as for 20 odd secs and dies any ideas

functionoverfashion > kiwibbq 04/02/2018 at 09:23

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Sounds like it’s starving for fuel. Older stuff like that can have issues if you put ethanol-blended fuel into a system that’s been sitting, or that hasn’t had ethanol introduced before. I’d replace the fuel filter, and any fuel line outside the engine i.e. to the tank and maybe use a new tank (or just borrow one you know is good, from a friend, to see if that helps).

In a case like yours the first thing we’d have done would be to hook up one of our own clean/fresh/good fuel tanks and see if it runs well on that.

If that doesn’t help, check the fuel lines inside the engine for cracks. If there are any that are easy to reach and replace, try that also. Rubber fuel lines don’t last forever, and don’t especially like to sit for long periods of time dry, either.

Desperate for the lake > functionoverfashion 05/27/2018 at 21:16

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Help! After seven years we got a new motor for our boat after it cracked. We took it out successfully once, now it won’t start. We have tried so many things. Replaced the starter, new fuel filter (have removed all the old gas and replaced the filter several times), kill switch is right, have tested voltage, checked the fuel lines, tried it in neutral ... my husband has tried it all, spark plugs. Boat will crank but will not turn...It’s flooding the engine. He is not priming. It’s a 2001 chaparral stern drive.

Mikezxx > functionoverfashion 08/12/2018 at 20:58

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I just lost all power at the key. When turned none of the gauges work. Today I see the power cabke at the starter broke. Would that cause the now power problem?

functionoverfashion > Mikezxx 08/12/2018 at 21:23

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you probably have other bad connections as well, and/or could have blown a fuse with the flooding issue... check both ends of main power wires to start. 

burnelo > functionoverfashion 06/23/2019 at 20:01

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Hello! Just bought a 2008 sea doo sportser and the second time out, we stopped and then couldn’t get it started again. I guy with a jet ski had some jumper cables and he  could jump it to get it started but as soon as he took the jumper cables off it would quit. Any ideas?? Thank you for any help you can give me

functionoverfashion > burnelo 06/25/2019 at 08:52

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It sure sounds like it’s not charging. Test the voltage at the battery when it’s off, it should be 12.5 or so, and when it’s running, more like 14. Now I suspect your battery is also dead and could at least use a good overnight charge on a trickle charger as well. 

burnelo > functionoverfashion 06/27/2019 at 17:57

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Thank you so much!! Your response has been so helpful to us!! We are putting the tri ckle charger on and will see how things go  from there. Hope you have a great weekend!!

burnelo > functionoverfashion 07/03/2019 at 13:30

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Had the trickle charger on for a couple of days but no luck starting the boat. Took the boat to Battery Source which checked the battery with a tester and it was dead. Bought a new battery and boat still won’t start. (Thought it might be the alternator but I’ve read this boat doesn’t have an alternator)  Can you steer me in any other directions of things to try?  Thank you so much!!

functionoverfashion > burnelo 07/03/2019 at 14:10

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It will turn over, like, spin the engine? Or does it just “click” but not really engage the starter? 

burnelo > functionoverfashion 07/04/2019 at 07:33

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It was the D.E.S.S. key!!  Now my problem is, if I don’t place the DESS key exactly right it wont start.  Almost like a short I guess. Going to see if I can purchase a new one.  I love your help!!, Thank you!  I live in Alabama, are you anywhere close? Thanks!

functionoverfashion > burnelo 07/04/2019 at 22:03

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Interesting, could be either end of that key I suppose. Glad you were able to get it going! I’m not near Alabama unfortunately...

Whitmer > functionoverfashion 04/15/2020 at 15:41

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Hello, we have a 98 Nitro fish and ski boat. Last summer, we ended up buying 2 new batteries. One day we were tubing and it just died and we had to get towed back to shore. It got cold and we havent done anything with it, however, now that its warming up, we decided to try and check to see if it would start. We put a charge on the battery and nothing happens. No lights, no beeps, nothing. Could it possibly be fuses? or???

functionoverfashion > Whitmer 04/15/2020 at 17:32

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It kind of sounds like it’s not charging the battery(batteries?) properly. Does it normally have two batteries, or did you have to replace the single battery on two occasions? Did you test voltage at the battery with the engine running last summer? It should be about 14 volts with the engine running, if the charging system is working properly. 

There is likely a main fuse or breaker, but that shouldn’t have tripped unless something happened. It would be inside the engine somewhere... 

What kind of engine does it have? You might be able to find a diagram online that’ll tell you where to look for power, and you can trace from the battery downstream to see where it stops.

bwest19 > functionoverfashion 06/20/2020 at 10:02

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Just bought a 1995 Four Winns Horizon 190 with the OMC Cobra 5.0 EFI. Engine number 50FAPHUE. Basically a 302 ford. This boat hasn’t been used much the last 5 years, basically winterized every year with very little time on water. I put 89 fuel from gas station in it and it ran fine one day, then next day ran for about 10 minutes and the motor would just turn and turn but not start. Replaced the fuel water separator that appeared to have rust in it. Removed fuel tank and had cleaned, and new rubber fuel line. Filled it up with marina fuel.  Ran great for about 5 hours and the same issue came back, quit while pulling tube, and again just turns and turns but wont start. Removed fuel line going to High pressure fuel pump and no fuel coming out while turning engine over. Put new low pressure fuel pump on, new pick up tube, new anti siphon valve and still no fuel. When i put key in on position i can hear LP fuel pump kick on. Kill switch is on, boat is in neutral. I have dropped about $1000 already, please help:)

functionoverfashion > bwest19 06/22/2020 at 09:40

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I wonder if it’s a faulty fuel pump relay. It’s likely to be a standard relay and you probably have more than one. If you can figure out which is the fuel pump, you can swap them around to see if it’s any different.

But since you had fuel issues to begin with, it could still be something clogged up from the original issue. Check the filter again. And if you can, try running the engine off a separate tank, like an outboard fuel tank, hooked right into the LP fuel pump. Maybe you’ve already tried that, but it helps eliminate everything upstream of the fuel pumps, and point you downstream from there. 

Mark Ezard > functionoverfashion 06/30/2020 at 17:06

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I have a 1989 celebrity 215 se with a 5 .0 v8 mercury motor boat was running stalled cranks over gets gas no spark. Replaced the coil no spark same thing.

Unhooked the kill switch moved it in and out started right up. So I replaced the kill switch back to square one cranks won’t start. Put back in the old kill switch and no start .running out of ideas please help 

functionoverfashion > Mark Ezard 07/01/2020 at 09:17

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If you bypass the kill switch entirely, does that make a difference? Like, physically connect one wire to the other - that’s all a “working” switch would do anyway.

So when you had it running last, was that on the new coil or the old one? Also, does this boat have points ignition, do you know?