Can`t find choke system on 50 hp 2stroke 1989 motor

[bogunnar]

Thanks!
I found this: Rodbolt and Yamaha Prime Start - Awesome Page: 1 - iboats Boating Forums | 302408

Am I correct? Mine is a solenoid using 12v from battery and controled by a thermal switch ( the toggle switch on remote 702 unit? maybe to override a failed thermoswitch or bad connectors?).

The other type is a wax valve. When cold = extra fuel. Heated by lighting
coil, so when warmed up = no extra fuel.

[99yam40]

From what Rod posted it should operate by ECU/CDI with input from thermoSENSOR

I myself am not sure what it does and when on that old 1989 50 motor

It definitely does no operate like my 1999 C40, which is a prime start model

[boscoe99]

I am now guessing that it works via activation of a toggle switch or key switch at the helm. But...

Let's hope Rodnut comes by with an answer.

The SM shows the solenoid being connected to the blue wire that is in the ten pin harness.

[99yam40]

Does that SM show where the other end of that Blue wire ends up?

Or maybe the OP can trace it to see

[boscoe99]

Does that SM show where the other end of that Blue wire ends up?

The blue wire is for what I always thought was for an electric choke. Electric choke as in a solenoid pulling on a rod to close a plate in the carburetor.

The blue wire runs up the ten pin harness to the key switch or to a toggle switch. Pushing the key in or pressing the toggle switch applies 12 volts to the blue wire.

Apparently it can also be used to activate the fuel enrichment solenoid. On a carburetor that does not have a choke plate. I did not know this. Too much to know about Yamaha's. And that is just one brand of motor.

Rodnut can confirm or deny. Where is he?

[boscoe99]

Illustration on the left is from the SM wiring diagram. Shows the blue wire from the enrichment valve leading to the ten pin coupler on the engine harness. It crosses the connector and runs to the helm.

Illustration on the right is from the SM carburetor section. Shows the two leads from the valve which are also shown on the wiring diagram.

[99yam40]

I just thought your 1989 SM would show where the blue wire went to if it showed it hooked to the enrichment solenoid on one end.
Maybe it does not show the other end at helm

If it just goes to the key or toggle then it would be only manually operated not automatic like Rod mentioned he thought it did

[boscoe99]

I just thought your 1989 SM would show where the blue wire went to if it showed it hooked to the enrichment solenoid on one end.

If it just goes to the key or toggle then it would be only manually operated not automatic like Rod mentioned he thought it did

Remember the V76 motor apparently uses automatic engagement of the valve. For starting, for acceleration and for detonation suppression.

The 40 valve is different.

An enrichment valve is not an enrichment valve is not an enrichment valve. Or, it is.

I report. You decide.

[99yam40]

I cant remember much about the system on the 50. the V76 I can chat with you about.

best I recall on the 50 it used a thermoSWITCH for overheat detect and a thermoSENSOR for ign timing when cold and cold enrichment,all con*****ed by the ECU/CDI.
if I make it by the shop this weekend I will try to look it up.
ya gotta remember in that time frame I worked on gray boats not play boats.

We will just have to wait on Rod to have a look to see what operates it

Of course the OP could do a little testing and tracing also.
we will have to wait and see which one posts back sooner

[boscoe99]

We will just have to wait on Rod to have a look to see what operates it

Of course the OP could do a little testing and tracing also.
we will have to wait and see which one posts back sooner

Ya think that rodnut has seen it all by now or does some old stuff still cross his work bench that he has not seen before?

[99yam40]

I believe he has said in the past he does not like to work on those old motors, may turn them away, too much problems when opening them up

[boscoe99]

I believe he has said in the past he does not like to work on those old motors, may turn them away, too much problems when opening them up

Yep. And probably too much time wasted trying to figure out/remember how a particular motor works, given that there may be some differences.

[almetelo]

My buddy 50DEO have a toggle momentary switch on the 703 control box

[boscoe99]

My buddy 50DEO have a toggle momentary switch on the 703 control box

What device on the motor is it activating? A choke plate or a solenoid valve?

Is the toggle switch actually on the 703 box or on an adjacent panel?

[almetelo]

At cold start by pressing that switch the carb solenoid is activated since is not necessary press that switch to resart motor again (unless some hours/days later)

The switch is on 703 box between the ignition key and the lanyard switch