So how is your engine running these
days? Many boaters, myself included, often go days or weeks without
thinking about that. But from time to time, the motor will hiccup or
stumble and will remind us that it if we let her get too far from our
mind, she’ll eventually get fed up with the inattention and let
us down.
Hopefully, you’re also like me,
and you don’t let it get that far. You do pay attention more
often than not. You take time to check the fasteners, lubrication
points, engine temperatures or the coolant indicator stream. What I
mean is you take time to show her you care, right?
When it comes to your motor, there are
certain necessities that you cannot overlook. You’ve got to see
to its mechanical needs. This includes items like fasteners and
anodes, but probably most importantly, this involves lubrication of
wear or friction surfaces. And you’ve got to make sure she gets
the power she needs, so the electrical systems from the charging and
starting systems to the ignition systems must be kept in good working
order. Luckily, there is not a lot of maintenance involved with
electrical systems. Maintain the battery, make sure the wiring
harness and connection are not damaged or corroded in any way.
But, off all your boat motor’s
needs, arguably the MOST important is your engine’s need for
fuel. I mean, at the end of the day, if there is no gas, there is no
go, right? So the care and feeding of your fuel system should be a
primary concern.
And again, thankfully, there is not a
whole lot of necessary maintenance that your fuel system demands.
First off, make sure you keep the fuel tank filled with fresh,
high-quality fuel. If the fuel in the tank is old, stale or
contaminated, then the motor will not run properly. If you leave
untreated fuel in the tank for more than a month or two, evaporating
hydrocarbons will eventually render the fuel almost useless. And, if
the fuel evaporates from the float bowls of the carburetor, it will
leave behind a gum-like material that can plug sensitive needles,
jets and passages.
It’s funny, but some people are
under the impression that carburetor tuning is a regular maintenance
task. But honestly, it’s not. The idle or high-speed mixture
screws should not require any attention unless something major has
changed, like the motor or the carburetor was rebuilt.
If the motor was running correctly
before it was put into storage, but doesn’t run right
immediately after removal from storage, the fuel supply and fuel
system are probably the first places I’ll look. And, this is
true even if the motor ran correctly for a few outings. Keep in mind
that gum or varnish which forms inside an improperly stored
carburetor may take a few hours of operation to brake loose and
suddenly clog a passage. Therefore if an engine performance problem
pops up early in the season, you MIGHT want to look at the fuel
system.
But when you do, don’t
immediately decide to adjust the carburetor(s) or don’t
immediately suspect the fuel injection system. Again, these are the
LEAST likely causes of the problem. When troubleshooting the fuel
system, take the same steps that you should take when troubleshooting
anything else. Start with the easiest items to check and the least
expensive items to fix.
Problems that occur only at idle or
only at high speed or load can easily be traced to the fuel system.
But before digging into the carburetor or fuel injection system
ALWAYS eliminate the fuel supply first.
If fuel starvation is a symptom first
suspect the tank vent, and the quickest way to eliminate that as a
possible problem is to operate without the tank cap installed or
closed.
Another easy diagnostic method that can
be used to eliminate problems with the fuel tank, pickup and lines is
to operate the motor on a “diagnostic” tank. Obtain a
portable marine fuel tank and hook it up to the motor, bypassing the
usual fuel supply. Whether or not this eliminates the problem, you’ve
already narrowed it down by half the possible components. If the fuel
pump is suspect, use a diagnostic tank that also has a fuel primer
bulb, when the problem occurs, have an assistant pump the bulb
repeatedly, which will in effect duplicate the action of the fuel
lift pump. Again, if the problem goes away, you’ve got your
culprit.
If you’ve decided it is time to
change or clean the fuel filter, there are a couple of basic types
which are all easily serviced or replaced. Most motors utilize some
form of an inline filter either between the fuel tank and pump or
between the pump and carburetor(s) or fuel injection vapor separator
tank.
Some inline filters are solid metal or
clear plastic housings which are clamped in the middle of two fuel
supply hoses. This style is easily removed and replaced by undoing
the clamps and carefully pulling the hoses free of the filter inlet
and outlet nipples.
Other inline filters consist of a 2
piece plastic or metal housing where a fuel filter bowl can be
removed from a filter cap. The bowl often threads into position or is
secured by a knurled knob which can be loosened by hand in order to
remove the bowl. Inside the bowl or cap of this style filter you’ll
find a removable filter screen. If the screen is not damaged it can
be rinsed in solvent and air dried (or VERY carefully blown dry using
low-pressure compressed air). When in doubt, this type of filter
screen is easily and inexpensively replaced.
Finally, many boats and some motors are
rigged using a disposable spin-on fuel filter or fuel filter and
water separator. These filters resemble automotive oil filters and
are removed or installed in exactly the same fashion. Often you’ll
want a strap or cap wrench for removal, as they tend to get stuck in
place after a season’s use. Once unthreaded, you’ll
normally find a small rubber gasket which again looks just like the
gasket on an oil filter. Before installing a replacement spin-on fuel
filter, be sure to lubricate the rubber gasket with a small dab of
engine oil (again, just like with a spin-on oil filter) to ensure a
good seal and to help make sure the filter comes off with ease next
time you need to replace it.
Many fuel tanks will contain a sock or
filter over the pick-up. These filters are usually life-time
components, but they can normally be accessed and changed by removing
the fuel pick-up from the tank. Similarly, many carburetors or even
some outboard fuel pumps may contain internal fuel filters which are
not periodically serviced, but which should be given attention during
overall or if you’ve encountered a severe fuel system
contamination problem. For details on servicing carburetors or fuel
pumps, you’ll need a good repair manual (such as a Seloc).
Only after you’ve eliminated the
fuel supply, the fuel tank, vent, lines, filters and pump, should you
suspect the carburetor or the electronic/electro-mechanical
components of the fuel injection system.
So what’s the morale of the
story? First, don’t let a little hiccup lead you down the road
to the carburetor or the Engine Control Module (ECM). And second,
don’t let the fuel supply get so old that it hiccups in the
first place.
Fig 1. Arguably the most important need
your engine has is for plenty of fresh, clean FUEL, so always make
sure you’ve got a good fuel source
Fig 2. If you suffer from fuel
starvation systems, first make sure your tank vent is open (if
manual) and is not clogged
Fig 3. If you’re uncertain about
the condition of the fuel vent, try operating the motor with the fuel
cap removed
Fig 4. In the case of built-in fuel
tanks, simply open the fuel door and test run the motor to see if
this relieves a fuel starvation problem
Fig 5. If you are uncertain about the
fuel supply, tank and delivery lines, another quick-check is to run
the motor on a separate portable “diagnostic” tank. This
tank can be temporarily rigged to supply an outboard, inboard or
stern drive, quickly eliminating half of the fuel system components
from your troubleshooting
Fig 6. Before checking the fuel pump,
make sure you’ve got clean fuel filter/water separators