Hi there… John Talley here with Boats.net… and welcome to our second video helping you
to diagnose ignition system problems on your outboard. Your outboard needs three things to
run just like any other motor out there: it needs fuel, air, and a spark. Now… the air is all around
you… the fuel is in the tank… but a lot of stuff has to happen in order to get that spark… and it
all culminates right here in the spark plug. Now let’s say your outboard won’t start… and you’ve
run through some obvious possible causes: like a pulled kill switch… no fuel in the tank… maybe a
loose connection… blown fuse… stuff like that… and you need to dive a little bit deeper. Well,
in this video I’ll show you how to inspect the spark plug and make sure it’s doing its
job delivering the spark you need to get going. So if you’re ready, I’ll walk you through it.
Okay guys… the first thing you need to check is well… are you getting electrical current down to
the spark plug? To test that… you need an in-line spark plug tester. Now there are several different
manufacturers out there. You just want to find one that is adjustable so you can determine just how
strong that spark is What you’re gonna want to do is pull off a spark plug wire… connect it to this
piece of test equipment and then the spark plug tester goes to the top of the spark plug. Now,
you’re gonna turn over the engine to see if you can see a spark jump across the gap on those two
points. If it doesn’t… you’re not getting any power… and if it’s dim… you may not be getting
enough. If it’s nice and bright? Well… that means you’re good. Now you can adjust the gap
between these two points… and the further out they are… if you can get a spark to jump across that,
that’s an indicator of a really healthy spark and that’s what we’re after. Once you‘ve done
one… if you’ve got a multi-cylinder engine… move on to the next spark plug until you’ve
tested all of them to make sure they’re all getting power. Because sometimes that will
help you isolate if there’s a problem on either one of your coils or the spark plugs themselves.
Now… you could be getting power to the plug… but then it’s still not getting the spark you need.
So pull the plugs and check them out one by one. This can tell you if your plug is okay… and give
you clues to tell you if other stuff is going on inside your engine. For example… say you pull the
plug and you see oil on the electrode. Now in a 4-stroke… that can mean you’re getting oil past
the rings or gaskets or maybe even a valve seal and it’s getting down into the combustion chamber…
now in a 2-stroke, it can mean, well, there’s too much oil in your fuel mixture.
Now if either one of those is the case… you can swap out that plug… but you’re gonna have to
address the problems otherwise it’s just gonna foul the plug probably sooner than you want.
The other thing you might see is carbon on the electrodes. That can mean the motor is set
to run too rich… but it can also mean you’ve got something going on inside of your intake that’s
restricting the air from getting down into the cylinder… which
by extension also ends up causing it to run too rich… relative to what the available air is in the
cylinder. Now that’s a long way of saying that something may have built a nest in your intake
and you need to make sure that it’s clean. Now on the other end of the spectrum… you
might see white on the tips of the plugs… and that can mean the motor has been running way too
lean… and after a while… that can take a toll on your motor because a lean running motor tends to
run a lot hotter… and that could be doing damage to the engine. Ask me how I know.
One bad tune wiped out an engine in one of my vehicles. It was not pretty. It got so hot,
heated up a valve to where it broke off and then turned the engine into a blender. Not a good day.
Now the last thing you want to check is the spark plug gap. You can check this with a feeler gauge…
or they have feeler gauge tools that are made for a spark plug so you can adjust it,
and you wanna make sure that it’s set jurt right. They’re usually set where they need to be…
but you’ve got the plug out… so why not go ahead and check it.
So now that you’ve done a visual inspection… you’ve already checked and you know you have
power getting to the spark plug… all that’s left is to actually see if it’s making a spark.
Now to do this… You’ll want to reconned to the plug wire… to the spark plug with it pulled out.
Keep it out and then put it on a ground somewhere on the engine. But before you do this… you’re make
sure there isn’t anything flammable around… because you’re about to bring a spark into an
environment and believe it or not, that can ignite if you’ve got any type of open fumes nearby. Also,
keep it away from the spark plug hole itself because you never know… you might have some
unignited fuel in there that may come shooting out and make a nice little blowtorch towards
you… and I don’t think you want that either… Now what you want to do is hold the end of the
spark plug—the tip—on a piece of metal. Of course it has to be unpainted, so look for
a nut or bolt or bracket so you can get a good ground and then touch the metal on the spark plug
to something metal on the engine… could be the engine casing… a bracket of some sort… it just
has to be metal so you can get a ground… then… turn the motor over and see of you see a spark.
Now… if the spark is yellow or orange… that means the spark plug is weak
and you might want to change the plug… assuming that you got a nice, bright light when you
tested your current running to the plug. You want that spark to be blue… or a purple
color--- that indicates you’ve got a really good fire. If you do… get the plug back in and repeat
the process if you have a multi-cylinder engine and check the other spark plugs.
No once you’re done… and you’ve got other spark plugs that don’t look quite right? You plobably
just need to go ahead and replace them all, and we have a few videos showing you how to do that.
Now… if you’ve already come this far in the testing… you’ve already removed the plug or plugs…
but just a couple of points to remember as you’re going to put it back together: don’t cross-thread
the new plug as you’re going to install it… because then you’ll have a real mess. Also…
check with your manufacturer… because some of them recommend getting a thin coat of some type of
dielectric grease or a non-seize lubricant. But be very careful of the brand of anti-seize that you
use. Make sure it is a marine grade before you go using it on the tip of your spark plug. The
other thing, you don’t want to over-tighten them. Get them hand tight… and then somewhere between a
quarter and three-quarter turns should do it. But keep in mind, that is for a new spark plug. Once
that washer has been compressed, it doesn’t take near that far to get it back to torque.
So, if you’re re-using your plugs, make sure you follow the torque specifications
for that particular plug. Now the plugs will probably have some specifics on the packaging.
Well guys, that just about wraps it up. Just a couple of simple tests
and some observations will let you rule out the spark plugs or replace them if that’s the source
of your ignition problems… Now if you need spark plugs or anything else for your outboard… come see
us at Boats.net and we can get you taken care of. If you have any questions or comments, why don't
you leave them in the section below and I'll do my best to answer them. Hey, if you like what
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working on or talking about next. We just want to say thank you for shopping here with us at
Boats.net, and we will see you in the next video. Y'all have a great day.