| It's an ever present thing. Our PWCs need fuel to run, and
oil to keep them lubricated. The fuel system of our beloved (well most
of the time) watercraft is all too often taken for granted. How can
I say such a broad and sweeping statement? Surely not because I want
to! The tuners that are out there that have paid their dues have had
these experiences; many times it results into molten globs of aluminum
somehow staying attached to the connecting rod! I've done it, along
with other seasoned tuners, as well as experimenters. Who it hits the
hardest, are the people who simply just add fuel to their craft and
ride. So many times to have their riding time cut short or possibly
"ruining the weekend for everyone". You know, the relatives
that waited all winter to ride uncle Bob's jet ski!! Not to mention
the family that gets let down by PWC failures.
There are very common things that happen to fuel systems that
we can prevent from ever becoming an issue. ALWAYS BE CAREFUL WHEN
HANDLING GASOLINE. NEVER TAMPER WITH THE FUEL SYSTEM WHILE THE ENGINE
IS RUNNING. 
People with Sea-Doos, don't just clean your sediment bowl, inspect its'
screen very thoroughly for foreign material and the content of the "stuff"
in the very bottom of the bowl. Everything you find or don't find helps
tell a story of your fuel systems condition. If you are dealing with late
model S/Ds ('98up) and see some dark-orangish thread-like material in
your sediment bowl, you probably have an issue with internal fuel line
decomposition. All too often this was found after the machine had been
ran so "lean" that major engine damage had already occurred.
 The
thread-like material actually passes right on through the sediment bowl
screen, and on its way to the internal filters inside the carb bodies
stopping necessary fuel flow.
The cure: Replace all
fuel lines with proper replacement fuel line. For you do-it-yourselfers,
buy the good stuff (new fuel line). For those who would opt to have it
done by a known good technician, make sure that the highest grade fuel
lines are used. I use NAPA supplied fuel injection grade hose. It has
worked and proven to hold up over years of normal useincluding neglect
and all that bad stuff we do, you know, slimy hulls and all. It doesn't
tend to "break down" and rot apart. Make sure when reinstalling
fuel lines at ALL connections, that they are AIR TIGHT!! Use high-grade
clamps, high grade zip-ties, making sure every fitting is important!!.
Running clear fuel line that hardens, NOT GOOD!!! Stick with the good
stuff, not what may look cool. To properly repair one of the later systems
you must start at the source. Clean the fuel tank. A task that isn't so
easy anymore!! Some tanks you could remove out of the machines in minutes,
very few anymore! So the task of getting all of the crud out of your tank
can be a challenge. We use an electric fuel pump with an extension of
hose that'll reach the very bottom of the tank and pump it into a waste-fuel
container.
The tank is usually accessed through the hole the
fuel baffle tube is mounted in, for two reasons. First, the baffle tube
itself has a filter on the end. It's a screen that is easily knocked off
 when
removing the baffle tube from the tank! So remove carefully. Also beware
that the screen on the end of the tube retains the float inside, if it
falls into the tank, you can usually retrieve it with a coat hanger, its
very magnetic. If it's dirty, clean it! Secondly, this gives the best
access to removing the fuel tanks leftovers. When you have removed as
much fuel as possible, (you'll never get the last little bit with the
pump), then maybe a coat hanger and that old tee-shirt that your wife
hates so much, can be an easy way 
to finish the clean up.
From there, it's time to clean the
fuel selector valve. If corroded badly replace this piece, it's a low
cost item. If it looks to be in good shape take it apart and look for
blockage and damaged o-rings, only if you're comfortable with disassembling
the device. If you  have
any doubt about your ability to do this without making mistakes, buy a
new one. Incorrect assembling of this can end up with serious engine damage!!
From there it's time to pay some attention to the fuel sediment
bowl assembly. Contrary to much belief, the fuel sediment bowl that comes
standard on your Sea-Doo should handle your fuel systems needs as far
as keeping the contaminates away from the end of the line, your carbs
and 
their filters. One thing we see very often are sediment bowl assemblies
that have NEVER been cleaned, or those that have been semi-molested by
less than careful hands installing or removing. Everyone with an X-4 hull
knows that they didn't give much thought to the accessibility of the little
$@#*. These are the ones that actually can  be
very easy to cross thread, pinch the o-ring, crush the screen, etc. All
of which will lead to starving for fuel, and an imminent lean condition.
Once again poor performance or engine damage. We have had many complete
engine rebuilds on many occasions where the o-ring was simply missing,
causing a severe lean situation and the operator kept running the unit
till she wouldn't go anymore.
When you have a lean condition
such as this your craft will give you warning signs before complete destruction!!
Hesitation, bogging, poor idle condition, losing rpm at high speed, idle
poorly yet will run ok above the 4000 rpm range, fuel fouled plug or plugs,
shutting off at high speed, accompanied by sit-a-minute and restarts,
etc. Granted a lot of these signs are only going to be picked up by a
"knowledgeable ear" or "knowledgeable seat of the pants
tuner", which are gifts that some tuners have. It is a gift, but
a lot of it is good ole common sense.
Avoid any kind of fuel
additives unless they are specified for your craft by the manufacturer.
If your machine is going to be stored, FOLLOW THE DIRECTIONS
IN YOUR OWNERS MANUAL!!! It'll save you lots of headaches and could
avoid a big slam to the wallet, or purse which ever applies!
Wow, all this talk about fuel systems and we haven't even gotten to the
carbs yet. The last filters in the system are the ones located within
the carb bodies. These filters should be reasonably clean if the rest
of the fuel system has been maintained; this requires nothing more than
fueling from a known good fuel source, and cleaning your sediment bowl
often. Well, the fueling from a known good source isn't always so easy.
Try to use fuel sources that are busy (fresh fuel in the tanks). That
also means they move a lot of volume of fuel, hoping that will mean they
maintain their filtration systems properly, hoping! Didn't mean to down
play the ease of finding consistently reliable fuel sources. When fueling
at an unknown source, after a few minutes of riding simply inspect your
sediment bowl. If water is present, it'll be in the lower portion of the
sediment bowl. Dispose of properly, reinstall the bowl assy. Carefully.
These are ways to avoid the contaminates from getting to the carb filters
and make your craft run poorly or suffer damage.
How about
when it has already reached the carbs? Time to clean/rebuild them, coupled
with the aforementioned ways to clean and keep clean the fuel supply clean.
For those who have to deal with EXTREMELY HARD to control fuel
quality, we have a way to solve that also. Using a high-volume Mercury
Quicksilver filtration system. It has a spin-on filter much like an oil
filter spins on and is easily mountable. We carry the systems. Should
be rarely needed, but it is "bullet proof". High volume, nothing
gets past it.
If the carbs have to have to be removed and
be cleaned and or rebuilt, make sure you have thorough knowledge of the
system and if not maybe you could remove them and have a knowledgeable
technician do them for you at a reasonable rate. For all you salt water
people, we face a tougher rebuild/cleaning, due to the corrosion that
is almost always present, especially on some of the older units. The flame
arrestor does a good job of making rinsing the carbs externally a task.
Make sure you get in their well when rinsing it down. It pays in the long
run. On the average I'd say only a small percentage of carbs that need
servicing and cleaning need a complete rebuild kit. The most common needed
diaphragm is the round main metering diaphragm, mostly because it has
an atmospheric vent that will allow water to sit in side the metering
diaphragm cover, causing decay of the diaphragm eventually. So buying
pricey carb kits when you don't usually need them, is a waste of $$. The
complete Mikuni brand kits are $39.95-$49.95, the diaphragm mostly needed
is about $12.00 or close to that price. But if your unit is more than
a few years old, replace all internal gaskets and diaphragms. Always use
new carb base gaskets! Cut no corners!
I really wasn't going
into carb rebuilding in this tech article but here are some things to
look for that some don't when rebuilding. Inspect the surface of the base
of the carb if it isn't 100% flat, 
resurface it and inspect closely the mating gasket surfaces at the intake
manifold, if the carbs have a lot of hours on them, check for throttle
shaft fitment at the nylon bushings they rotate on in the aluminum carb
body, should be tight, yet rotate freely. NEVER tighten down on your low
or high speed circuit adjusters, a light bottoming is all to use as closed.
Use a good dose of blue LocTite, at the appropriate areas, especially
at the mounting bolts.
Hope sharing some of the experience
I've shared will help people save down-time and money. 60-65% of the major
repairs we do can be traced back to lean conditions and/or lubrication
issues. Fuel is a lubricant and a coolant, an area for no compromise!!
Glen Perry
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