Conference vicki::boats

    1) Does your throttle control have a neutral accelerator advance? 
    
    2) Do you squeeze the primer bulb prior to starting it cold? (5, 6 or
    more squeezes!)
    
    I had a real tough time starting cold until I figured out how to do #1.
    
    I'd worry more about burning out the starter motor when experiencing
    long starts than I would about my battery!

    This sounds pretty straightforward.  If the motor starts easily
    by manually engaging the choke, check to make sure the electric
    choke solenoid is working.  Remove the cowling, turn the key on,
    then push the key in (or whatever the method is for engaging the 
    choke from the control box), and watch the choke to make sure it 
    opens and closes.
    
    If the choke is working, there should be no difference in starting
    between using the electric choke or engaging it manually.  If it's 
    not engaging with the solenoid, check to be sure the solenoid gets
    juice when you hit the switch.  If it does, the solenoid itself
    may be bad.  If not, check the switch and the wiring.
    
    Also, this may be too obvious but be sure you pump up the fuel
    line with the squeeze ball before trying to cold start.  Most
    fuel systems will lose pressure after sitting for several hours.
    This can cause a similar problem to what you have.
    
    FWIW, newer model OMC's do not have a choke.  They have a cold 
    start valve, which injects extra fuel into the motor.  The fuel
    line *must* be pumped up, and the key is pushed in several times
    to inject enough extra to fuel to richen the mixture so the motor 
    will start.  If it continues to run rough after starting, it's 
    sometimes necessary to continue pushing the key for a brief period 
    until the engine warms up just a bit.
    
    Rick

	1:   How old is the gas?
		I've found that gas that has been sitting around awhile makes
		my Mariner (a Merc in a gray flannel suit) start hard when cold.

	2:   How old is the oil?

	3:   What oil/gas mixture are you running?

	4:   Do you manually mix your gas & oil or is this done for you?

    I had a '73 65HP Johnson that always seemed to be hard to start when
    cold, or when it would sometimes stall when hot. It had a toggle switch
    on the rear of the control box which choked the engine when manually
    moved. It also had a manual choke lever on the lower front but who
    wnats to walk beck each time to engage and remove the choke. I tried
    the method already suggested regarding checking the choke solenoid. 
    While doing that I found that the solenoid did not move or only moved a
    small amount. When I applied voltage to it directly, however, it worked
    fine. I traced the wires and found that voltage from the toggle switch
    passed through some kind of temp. sensor in the engine block and seemed
    to try to adjust choke closing based upon engine temperature. I did not
    attemp to trouble shoot this system, but instead easily bypassed the
    temp. sensor and wired voltage directly to choke solenoid so you got
    full choke when the toggle was moved. This seemed to cure both the cold
    and hot(after stalling) starting problem. This was accomplished by
    moving the solenoid wire to a different terminal on the terminal block.
    I do not know if yours works the same.
    
    Larry
         

    Outboards are probably not theoretically harder to start (gas+spark =
    start on both 2 and 4 cycle engines) when in good repair.   But they
    sure seem to be much more sensitive to minor fuel delivery and
    carburetion problems than 4 cycle engines.  An unchoked 4 cycle engine
    will sputter and not start instantly when cold, but start it will.  Two
    cycle engines with choke or primer malfunctions may *never* start.
    
    One of the things I never understood is why the fuel pump on a 4 cycle
    engine seems to be perfectly capable of supplying fuel at cranking
    speeds (you don't squeeze a primer bulb before starting your car,
    right?), but my Johnson outboard shop manual flat out states that the
    fuel pump on the o/b can't deliver adequate fuel at cranking speeds,
    hence the need for various automatic and manual priming mechanisms.
    Why the difference? 
    
    

RE: .5
>> One of the things I never understood is why the fuel pump on a 4 cycle
>> engine seems to be perfectly capable of supplying fuel at cranking
>> speeds (you don't squeeze a primer bulb before starting your car,
>> right?), but my Johnson outboard shop manual flat out states that the
>> fuel pump on the o/b can't deliver adequate fuel at cranking speeds,
>> hence the need for various automatic and manual priming mechanisms.
>> Why the difference? 
   
There's a very good reason for this. The mechanical fuel pump in your car 
is just that, it is mechanically actuated by a lobe on your engine's cam
shaft.  It operates at any speed, although of course slower at lower rpm.

Since 2 stroke engines do not have camshaft to drive the fuel pump, the pump
is driven by pressure pulses in the crankcase.  Each time a piston is on the 
downstroke it pressurizes the crankcase.  This pressure is exerted on the 
fuel pump diaphagm, and is converted to vacuum pulses by the fuel pump for 
sucking fuel out of the tank.  At cranking speeds the fuel pump just doesn't
generate enough vacuum to draw fuel out of the tank and fill the carb. 

These pressure pulses in the crankcase, by the way, are the reason that 2 
strokes require some sort of a one-way valve, usually a reed valve, to 
prevent the pressurized fuel and air mix from blowing back out through the 
carburetor.  There are other methods too besides reed valves, some 2 strokes 
use a rotary valve, which is driven off the crank and exposes a port at the 
precise time that fuel is to be drawn into the crankcase.  Martin outboards 
of the late 1940's and early 1950's used a patented poppet valve system, very
similar to the valves in a standard 4 stroke.  But this is getting off the 
subject a little...   8^)

Rick

RE: Note 933.5  
>> An unchoked 4 cycle engine will sputter and not start instantly when 
>> cold, but start it will.  Two cycle engines with choke or primer 
>> malfunctions may *never* start.
   
Forgot to answer this one, which also has a simple explanation.  In your
car (or most other 4 strokes), you can overcome a non-working choke by 
pumping the throttle several times, allowing the accelerator pump to squirt
extra fuel in and richen the mixture.

Most 2 strokes do not have an accelerator pump in the carb.  You can pump
the throttle all day long and nothing will happen.  So you're right, with
a cold 2 stroke, no choke + no accelerator pump = no start.

Rick

    Good info.  You've confirmed my assertion that 2-cycle engines have
    more *potential* for not starting properly. 
    
    Howcum large 2 cycle engines don't have electric fuel pumps?  If I had
    a 300 horse Johnson V-8 I'd feel pretty silly squeezing a primer bulb
    :-)   (and don't say you'd lose manual start capability - I tried
    rope-starting my 115 once - it can't be done )
    
    

    As always its the cost vs. benefit ratio.  In a large 2 stroke outboard
    I assume that the pressure pulse type fuel pump is adequate.  To put
    in an electric or mechanical pump would add cost to the OB and reduce
    their competative price stance compared to other mfgrs. 

OMC offers an electric "priming pump" for its larger engines, which
precludes the need for the priming bulb. But, as far as I know, the
separate oil line still requires a squeeze bulb.

Art

    One of the reasons that a 4 cycle starts easier is not the fuel pump
    but the carb itself. The fuel required to start a 4-cycle actually sits
    in the carburetors float bowl, in sufficient quantity to start and run
    the engine for a brief period of time. During this period of running
    the fuel pump "catches up" fills the bowl and then maintains sufficient
    fuel supply to keep the bowl at the correct level. All priming of the
    engine "pumping the accelerator" also draws upon this supply in the
    bowl.
    
    2-cycles carbs do not have such facilites and hence the priming of a
    fuel supply with the bulb. Also, the two cycle engine, as mentioned
    previously, must overcome backpressure on start and therefore the fuel
    supply needs to be pressurized. When running, a 2-cycle fuel pump is
    more critical at supplying pressure than actual fuel.
    
    An electric pump could supply fuel at pressure. But the more logical
    place for installation of an electric pump would be at the fuel tank
    outlet or inline somewhere to the engines. Yes engines, as one pump
    would service both engines.
    
    The real issue is more one of cost than technology. Automobile/truck
    EFPs do not have to meet spark suppression requirments, interesting
    enough. Ones for marine use probably would have to (definitely for the
    bilge mounted ones).
    
    IMHE (In my humble experience) most 2-cycle starting problems are a
    result of improper procedure; but then again pilot error is blamed for
    everything.