Question choke solenoid on my 73 115hp Johnson

[teslaman]

The automatic choke never did work correctly before my motor blew, I always used the manual choke. Since I've installed a rebuilt powerhead, I've gone ahead and reconnected the choke solenoid in the configuration given by my Clymer and SELOC manuals.

The solenoid, plunger, and spring linkage are there but the plunger spring is not so the plunger does not get pushed back up at this time. I've ordered a new spring and its on the way.

The question that I have is about its operation. I've followed the wiring schematics and the plunger does go down when the choke switch is activiated. But the plunger goes down a little bit when the ingnition key is turned. I know that the choke switch is wired into thermal thermal switch that keeps the choke from fully opening until engine temp reaches a threshold, but is the plunger supposed to activiate at all when the ingnition key is turned and the choke switch is not activated? Of course, the lack of the plunger spring to resist the force from the magnetic field seems to make it close more. Is this behaviour normal for the choke solenoid or do I have a wiring issue?

 

[ezeke]

Re: Question choke solenoid on my 73 115hp Johnson

Most of the thermo switches were disabled by service departments in the 1970's in accordance with SB #1335. You may wish to do likewise:

"Disconnect the thermo-switch leads from terminals #3 and #4 and tape. Move the remaining purple wire with yellow stripe from terminal #4 to #1. Install a jumper across terminals 1 & 2."

I have a pdf copy of the Service Bulletin, which applies to many models. If anyone would like it, send an email.

 

[tschamp20]

Re: Question choke solenoid on my 73 115hp Johnson

email has been sent thank you

 

[teslaman]

Re: Question choke solenoid on my 73 115hp Johnson

I sent you an email too!

Thanks

 

[teslaman]

Removing the warm-up feature

Removing the warm-up feature

Is it necessary to remove the warm-up feature if the plugs don't foul and the other problems do not occur? Otherwords, is it best to keep the warm-up feature if the engine runs smoothly with it?

 

[ezeke]

Re: Question choke solenoid on my 73 115hp Johnson

You said "The automatic choke never did work correctly before my motor blew".

This was the alternative.

If you can assure yourself that the 30+ year old sender on the engine is working properly, and that the choke is cutting off at the proper time, and staying off when it is not needed, then I would not see any reason for concern.

In either case, you still have the choke toggle working from the control for cold starts.

The warm-up lever on the control simply advances the throttle and has nothing to do with the choke.

 

[teslaman]

Re: Question choke solenoid on my 73 115hp Johnson

The reason why the old choke didn't work properly is that the previous owner had it connected incorrectly and I think that the solenoid was missing the spring that goes under the plunger. In short, I always had to start the boat using the manual choke.

I'm not sure how old the sender is. The powerhead has been rebuilt, but I do not know if a new sender was installed.

I can easily disconnect the sender and perform the mod. If that's that safest bet, I'd rather go ahead and do it.

 

[Dhadley]

Re: Question choke solenoid on my 73 115hp Johnson

The reason for the bulletin saying to disconnect the wires from the heat sensor was that it was very possible to start a slightly warm engine and have the sensor put the choke on about halfway or so. It was possible at that point that the motor would flood, leaving the operator with a motor that didn't start. In some scenarios that could be bad or even dangerous.

It's better to disconnect the sensor and rely on the operator's judgement if choking is needed or not.

In the best of all worlds, removing the choke altogether and installing the newer primer system would be prefered. But if the choke system works for you, I'd leave it on.

 

[teslaman]

Re: Question choke solenoid on my 73 115hp Johnson

Gotcha! Thanks for the tip. I'll disconnect the sensor make the mod.