Electric Choke Question - Older 70HP Johnson Seahorse

[pede69]

Hi...

I am wondering if someone would please give me some tech advice on an issue I have on a motor I just purchased?

Motor: Older 70HP Johnson Seahorse. (I think a 1975)
Can not read model number.

Motor starts fine but revs really high.
If I move the choke rod manually, RPM will go down.

When I follow the red wire that is connected to the electric choke, (I think that is what it is) Pic's here: http://sonicinfo.org/boat/ , it goes underneath the dash. I have not got under there yet to see where it is tied in.

One question is... I believe that the red wire is positive but should it be 12v constant or only until the motor warms up or exactly how should this wire be hooked up?

When this wire is hot, if the choke is working, it should control the start up RPM, right?

Any other thoughts?

Thank you for you help,
John

 

[ezeke]

Re: Electric Choke Question Please

Re: Electric Choke Question Please

The choke solenoid is there to open and close the chokes in the carburetors for a cold start. It does this by enriching the fuel/air mix by closing off the supply of air and forcing the pistons to pull extra fuel through the carburetors.

The chokes should normally be needed only for a cold start. In the 1970's the choke solenoid was usually operated by a toggle switch at the helm.

 

[pede69]

Re: Electric Choke Question - Older 70HP Johnson Seahorse

Great... thanks...

So you are saying, use the toggle switch to choke motor until warmed up, then switch into off position?

Thank you,
John

 

[pede69]

Re: Electric Choke Question - Older 70HP Johnson Seahorse

Also... what is the lever on the control box that says "Warm Up T" ?

It did seem to make a difference when I tested it.

Thanks,
John

 

[ezeke]

Re: Electric Choke Question - Older 70HP Johnson Seahorse

The warm-up lever is used to advance the timing and open the throttles a little for a cold start. Have someone move the lever while you watch the movement at the engine.

You use the warm-up lever and the choke for a cold start. Let go of the choke when the engine fires, then gradually lower the warm-up lever as the engine warms up. You may need to bump the choke a few times to keep running while cold.

 

[pede69]

Re: Electric Choke Question - Older 70HP Johnson Seahorse

Thanks ezeke... that helps a lot.

One more question will do it I think

How can I manually test the choke solenoid for correct operation?
Just apply 12v to it an see if the plunger engages?


Thanks a ton
John

 

[ezeke]

Re: Electric Choke Question - Older 70HP Johnson Seahorse

The chokes need to close at the same time and completely to be effective. Take the air silencer cover off the carburetors and watch the plates while someone cranks the engine so that you can see what happens.

You can synchronize the plates with the linkage and then adjust the solenoid in small increments by loosening the clamp and moving the solenoid.

I don't see a choke switch on your remote control, so you may have a push to choke ignition switch - try pushing the key in with the key in the run position and see.

 

[pede69]

Re: Electric Choke Question - Older 70HP Johnson Seahorse

OK... I'll try that this evening, I have to leave for work now. I did notice that the key WILL push in.

Also there is a momentary push button switch next to the ignition switch that makes a clicking noise from the motor when pushed. I have not had someone else push it while I am at the motor to see just what it is doing. I can say that it is a LOUD click.

Thank you for all your help, I will be back on tonight.

Have a great evening,
John