2009 50hp two stroke starting problem - Emergency enrichment

[trose1985]

Hi All,

I have a 2009 50hp two stroke yamaha with around 20 hours on it. It used to cold start well. However, since a service about 2 months ago, the motor is a pig to start cold. It will either simply start (10% of the time), or will just turn over and over without firing. Once started the motor is a dream and has no problems running or starting. Had to load it up a few times now and its knocking my confidence around with the motor.

Ive had it looked at by someone else and they cant find anything wrong with it. As you would expect, it started for them. The only way i seem to get it going is by turning the emergency enrichment switch to 'off'. Motor then usually starts and after a few seconds will stall. But then i can often put the switch back in the 'normal' position and get the motor going. But this is crazy and i cant do this all the time.

Any ideas people?

Cheers

Tim

[99yam40]

what kind of service did you have done to it?

What is your starting procedure when cold starting?

[rodbolt17]

you should have 3 positions, close,normal and emergency.
closed shuts off all enrichment.
normal is just that.
emergency opens the enrichment for cold starts in the event of a non enrichment failure.

throttle angle means everything to its normal operation.

[trose1985]

I had only a basic second service such as spark plugs, gear box oil, impeller etc. No adjustments were made according to marine mechanic, however, i cant help but be a bit skeptical as motor was perfect when i sent it in.

Procedure for starting (prior to service and worked well) was to pretty much turn the key and it started with little trouble.

Now - following advice from Yamaha, i squeeze the fuel bulb a few times and turn the key. If it starts, i usually lift the fast idle lever to make sure it runs as i may not get it going again if it stalls these days.

When it is not starting i have not tried the emergency enrichment 'open' position yet, only in the 'closed' position.

Throttle angle should not have been altered, but if it has, is there an easy way to check that it is within spec? Im no marine mechanic.

Thanks for your feedback.

[throrope]

Our tlr 90 has the emergency enrichment lever as its part of the electronic style choke connected to the middle carb. Mine has a diaphragm accessible by three or four screws. If its damaged, that may be a culprit. A quick check of all connections - hose and wires - is cheap. An exploded parts diagram is available on this site through the parts purchase.

I'd also pull one or more of the bowl drain plugs completely and look for crud - classic indicator our lovely ethanol enriched fuel has on our good times. A 2009 is listed for ethanol compatibility, but a carb still has small easily clogged openings. After an expensive repair, I now empty the bowls and pump all fuel out and into the car if not using the boat for any length of time. No fuel, no fuel to go bad. I rigged a $26 automotive electric in-line fuel pump to a 12 volt plug with fuel hose and Yamaha fuel connector. I also drain the water separating fuel filter and turn our portable 12 gallon tank upside down with lid off so it evaporates bone dry.

BTW, the prices here are also the cheapest I've found.

Good luck and keep us posted.

[dorf]

I used to have one of these and it was always hard to start on the first start of the day.

Solution : Turn the key on and wait about 6 seconds or so (enrichment kicks in) push the throttle up a little( on 704 ? remote control push inboard to permit usage of the Free throttle- it will increase RPM), turn to start.When starts control RPM to about 1200 or so and then gradually bring to idle.

You have fast start lever so that should work even better using that.

[99yam40]

I had only a basic second service such as spark plugs, gear box oil, impeller etc. No adjustments were made according to marine mechanic, however, i cant help but be a bit skeptical as motor was perfect when i sent it in.

Procedure for starting (prior to service and worked well) was to pretty much turn the key and it started with little trouble.

Now - following advice from Yamaha, i squeeze the fuel bulb a few times and turn the key. If it starts, i usually lift the fast idle lever to make sure it runs as i may not get it going again if it stalls these days.

When it is not starting i have not tried the emergency enrichment 'open' position yet, only in the 'closed' position.

Throttle angle should not have been altered, but if it has, is there an easy way to check that it is within spec? Im no marine mechanic.

Thanks for your feedback.

probably best to take it to a Yamaha shop with techs that have certificates on the wall saying they have passed the training if you do not know much about these motors.

Sounds like the carbs need cleaning or the prime start system has a problem and dumping too much fuel if you have to put it in closed position to start.
If you raise the throttle too far at warm up it will cancel some of the prime start system.
If all is good shape it will run like it should bran new at factory settings

[dorf]

Also when you get to operating properly, install a Yamaha 10 micron water separating fuel filter in the system. Verify on board filter is not full of junk. Lastly fresh, no ethanol gas is most important otherwise it just deposits crap all through the fuel system.

[rodbolt17]

proper starting procedure is prime the carbs, turn the key.
it starts or its broke .
yes Virginia its that simple.

leaving the key on has NOTHING to do with anything.
enrichment valve power is taken from the lighting coil.
no flywheel turning no operating voltage.

best bet is to take it someplace that has at least 1 master tech and a minimum of fuel and electrical certifications on the wall.



like I say, linkage adjustment and proper enrichment valve and pump operation is critical.
by turning the valve to CLOSE you are cutting off ANY enrichment.
when you rotate it to emergency you are BYPASSING the enrichment valve.

either way its telling you its sick.
two strokes wont run sick long before you get a death certificate

[boscoe99]

[trose1985]

Firstly, i have to apologise lads. Im also about to reinforce my earlier comment about being "no marine mechanic"!!!

I double checked the emergency enrichment switch following the previous post (thanks for the diagram mate) and it turns out im actually switching the enrichment switch to "open" not "closed". So it would seem that for whatever reason it isnt getting enough fuel on cold start and I guess it still stands that the carbs need a look first to make sure they are not blocked.

[boscoe99]

Auto is just that. Automatic fuel enrichment.

Additional fuel is provided when the motor is cold but as the motor warms up the amount of additional fuel is reduced. When the motor is fully warmed up, the prime start device should not be allowing any additional fuel to flow to the motor.

On means that additional fuel will be provided all of the time. Maybe the correct amount when the motor is cold but too much once the motor is warmed up.

Off means that no additional fuel will be provided at any time.

[99yam40]

Just Make sure cold start is with switch in auto position not the closed

[boscoe99]

Maybe more than most will want to know about prime start, but here is some Yam literature that describes this feature.

[rodbolt17]

while the above picture works on a four stroke ONLY.

the electrothermal valve operation is the same for two stroke.

the two stroke simply adds a diaphragm operated pump and routes fuel to the intake manifold were individual pipes supply fuel under pressure to aide in cold start enrichment.

IF the diaphragm for the enrichment pump should tear it would flood the engine, that's one area that closed valve would help.
by closing the valve it shuts off fuel to the pump and therefore the enrichment system.

if the wax pellet,lighting coil or wireing should fail you could still turn off enrichment.

should the electrothermal valve fail in the fully extended position then by opening to open or emergency, you could start it cold with manual enrichment.

as two strokes have very limited intake manifold vacuum, especially at cranking, the four stroke style simply wont work.