Top 5 Reasons Your Boat Won’t Start

Here in the shop, we get a lot of phone calls from people who’s boat will not start. This could be for any number of reasons. Sometimes we are able to help them out over the phone as it is something very simple or other times the boat needs to come into the bay to be diagnosed by one of our technicians.


In this post, we thought we’d list the top 5 most common problems we encounter when it comes to your boat not starting. This is a good starting point for you if you are having this issue.


#5 Fuel



Either no gas or bad gas is a very common issue especially come spring. Maybe you didn’t add fuel stabilizer in the spring and that gas has been sitting in your tank over the course of the wintertime deteriorating. Or it’s very possible there is no gas in the fuel tank even with the gauge indicating there is. Fuel gauges in boats are notoriously unreliable and fail often.


A quick check would be to disconnect the fuel line on the engine, stick the hose in a glass jar and prime the bulb or crank the engine over to get a fuel sample. This will tell you the quality of the fuel or if you're even getting any fuel to the engine.


#4 Dead Battery



The dreaded dead battery scenario. The boat started up just find the last time you were in it maybe a month ago, a week ago or even an hour ago but now you turn the key and got nothing. Maybe some electronics were left on or the key switch was left in the ‘on’ position but either way you're looking for a boost. This will usually show up as slow cranking or no crank at all, maybe the lights show up very dim or the stereo will cut in and out indicating a low voltage at the battery.


If possible it is best to remove the battery and charge with a trickle charger and then have that battery tested as well before going out and using it again. If this is common issue for you, you maybe want to check out our post on battery switches here.


#3 Kill Switch



It’s always tough when you’ve been struggling to get the boat started for some time on a hot summer day, the kids are yelling and climbing all over the place and then you realize the kill switch isn’t hooked up! This is a lot more common then people think and it can happen to any of us. Sometimes we just get a little too eager to get our day started on the boat that we overlook the little things. Maybe it looked like it was on there but lots of times it can easily get pulled partially off, it looked like it’s on but it’s not actively engaged. Or maybe the kill switch itself has become faulty. Kill switch’s work by either allowing 12V to go through them or not. It does happen when the switch itself fails and needs to be replaced. This can be checked quickly if you have a multimeter handy.


#2 Primer or Choke



For your non-fuel injected engines out there this is for you. Whether it is an outboard or an inboard most carburetor engines need some form of priming or choking. This process allows more fuel than air to enter the combustion chamber to aid in cold starts. Allot of people expect their boat to be like their car when they jump in and just turn the key and go, sadly that’s not the case. On outboard engines, this can be achieved usually by pushing in on the key while cranking the engine over. This will activate the choke plates on older models and the primer on newer models. On inboard boats, priming is done by simply pumping the throttle 2-3 times prior to starting. This pumping squirts small amounts of fuel directly into the carburetor to help with cold starts. Most inboard carburetors are also equipped with a set of choke plates that will open and close automatically with the temperature of the engine. This is also a common point of failure and can be easily checked by removing the flame arrestor. A word of caution though with priming, just as the engine will not start easily without priming or choking it can be just as difficult if not impossible to start if the engine gets flooded. Too much fuel will also leave you banging your head to start the engine so make sure you know the proper starting technique for your engine. If you are sure a quick phone call to your service shop will help.


#1 Dirty or Loose Battery Cables



This is by far the most common issue we see in relation to no starts. This can be a tricky one to identify as well. Sometimes your engine will fire up with no issue and other times you get nothing. Lots of people misdiagnose this as a faulty starter or a dead battery. Always start at your battery cables and terminals if you are unsure and clean them until they look shiny. Many times the cable ends will look clean but really are not. They should be filed down until the ends are noticeable shiny and clean and then reinstalled and tighten accordingly. ABYC now advises all battery cables to be installed with a hex nut instead of the traditional wingnuts. So if your battery still has the old style wingnuts, run out and replace them with the proper sized hex nut. We see this issue most often in the spring after the boats have been sitting all winter. I highly recommend including this in your yearly maintenance even if you are not having issues, it is a good habit to get into. In some cases, the cable ends or so corroded that they just need to be cut off and replaced.




There are our top 5 issues for boats not starting. We realize that starting issues can be any number of problems but this is a good place to start. All of these issues can be easily identified and repaired by most boaters which will hopefully save you a trip into the shop and save your weekend. If you have checked all these issues and are still having problems then we would be happy to hear from you can help you out over the phone or book your boat in for service.

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