50 HP 2 Stroke Electrothermal Valve ?

[Yamaha 50TLRA]

Hey guys, I have a 2002 Yamaha 50TLRA 2 Stroke and the ( Fuel Enrichment Valve ) doesnt seem to be working, If I turn the key on and push in ( choke ) I get no signal with a test light.

It has always been this way since I bought the boat but I would like to get it fixed, It will start without problems but has to crank over about 10-15 seconds straight before it fires, and then will run fine after its warmed up.

Thanks for any help, Rick

[boscoe99]

What makes you believe that the choke switch activates the PrimeStart device?

The choke switch does nothing with respect to your motor.

The PrimeStart device is automatic. It provides additional fuel when the motor is cold and then progressively allows less additional fuel as the motor warms up.

The wires to the PrimeStart provide voltage only when the motor is running.

Is the emergency over ride lever in the fully counter clockwise position? You might want to go and read all about this in the applicable owner's manual.

[Yamaha 50TLRA]

Hi Thanks for the reply, So you are saying that I dont have a choke on this ? and pushing in the ignition switch does nothing as far as activating a choke goes ?


The Emergency override switch is in the correct position.

Thanks, Rick

[boscoe99]

Hi Thanks for the reply, So you are saying that I dont have a choke on this ? and pushing in the ignition switch does nothing as far as activating a choke goes ?

The Emergency override switch is in the correct position.

Thanks, Rick

Absolutely correct.

A choke is a choke and is only one type of fuel enrichment mechanism. Your motor does not have choke plates on the carburetors.

PrimeStart is altogether different and normally is completely automatic. To make it more confusing, there are many types of Yamaha PrimeStart mechanisms that have different means of fuel enrichment to facilitate a cold start. Yam even refers to their electronic fuel injection four stroke models as having PrimeStart.

Given the age of your motor I suspect that you have a carburetor issue that needs to be addressed. You might want to consider dismantling the carburetors to clean them in a heated ultrasonic cleaner.

[Yamaha 50TLRA]

I just did a complete carb cleaning the other day ( carbs were spotless ) and it still starts the same. It runs great when running with no problems.

I think the fuel enrichment valve works fine because when it starts the idle goes up for a bit and then comes back down, so this tells me its doing what it should.

So on the initial start, what assists the motor in cold starting ? It seems it just is the way it is ?

Thanks, Rick

[boscoe99]

On initial start when the motor is cold the PrimeStart device has a pin that is retracted. The pin being retracted allows additional fuel to flow to the motor to facilitate a cold start.

Once the motor is running it creates electricity. Some of that electricity is fed to the PrimeStart device. It starts to heat up. As it heats up the pin extends to close off the port that is allowing additional fuel to flow.

Perhaps your PS device is not working correctly.

[Yamaha 50TLRA]

Should there be some sort of power to that with turning the key on, Because something has to make it work ?.. I turned the key on and got no power reading on the test light at the source.

Well it does start and has never not started so at this point Im not to worried It just cranks a little longer at cold start up than Im used to, Had all Mercs before this one, Had to push in the ignition switch and I could hear the enricher clicking each time I pushed it in on the Mercs.

[boscoe99]

Power comes directly from the lighting coil. Not the key switch.

[dngharvey]

I own a 70hp with a 703 control and a 90hp with a 704. They are very different in the way you start up cold, took me a while to figure it out. The 70 is supposed to be an '88 and the 90 is supposed to be a '94. Can't find an i d tag on either one.
Elec choke on the 70 never worked but manual is an easy reach. The 90 has no choke at all, but there is a do nothing toggle near the ignition key.
They both start pretty easily and run well. The 90 needs nothing but a few 3 or 4 second cranks to start up after only checking the squeeze bulb.