Choke adjustment question..........

mrcj001

Petty Officer 1st Class
Joined
Jul 25, 2008
Messages
313
1975 135 Johnson


I`m confused with the choke adjustment......

After engine is started and at operating temp, where should the choke plates be postioned??

Right now, when engine is at idle the choke plates are open maybe 1/4 open,when I advance the throttle, they may open 3/4 of the way.

The choke selenoid works and pulls the plates closed, but seems to not let them open all the way.

I`m wondering if this has been causing my ocasional engine stalling.....too much choke at idle.
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Choke adjustment question..........

They should be wide open. Move them back and forth manually and see if the linkage is binding somewhere.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Choke adjustment question..........

They should be wide open. Move them back and forth manually and see if the linkage is binding somewhere.

Well now that depends.... If it is wired as it came from the factory, it has a warm-up position which partially chokes it while warming up. That is to help prevent the spitting and snorting and allow you to get it to idle sooner.

However, there was a service bulliten that told how to re-wire it to eliminate the warm-up function. Seems that in warm/hot weather they had trouble with over choking. Eliminating the warm-up choke puts it entirely under the driver's control.

Sounds like the question relates to a motor that is factory wired and acting just as it should.
 

mrcj001

Petty Officer 1st Class
Joined
Jul 25, 2008
Messages
313
Re: Choke adjustment question..........

Eliminating the warm-up choke puts it entirely under the driver's control.


I believe a couple of years ago, I rewired the choke selenoid per the service bulletin.....does the choke selenoid have a constant pull on the choke linkage if the wiring is not changed or correct??

So...at idle and warm, the choke plates should be wide open??

On the lower carb on the port side is a manual choke, it has three positions. All the way down in "choke ON". The middle position is where the choke can be activated by the selenoid and the third setting is choke wide open.

Why is this choke lever there...its not acessable unless the engine cover is removed, which is hard to do on the water.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Choke adjustment question..........

I believe a couple of years ago, I rewired the choke selenoid per the service bulletin.....does the choke selenoid have a constant pull on the choke linkage if the wiring is not changed or correct??

So...at idle and warm, the choke plates should be wide open??

On the lower carb on the port side is a manual choke, it has three positions. All the way down in "choke ON". The middle position is where the choke can be activated by the selenoid and the third setting is choke wide open.

Why is this choke lever there...its not acessable unless the engine cover is removed, which is hard to do on the water.

Turn the key off--if the choke plates are now wide open, but are partially closed when the key is on (cold), then the warm-up function has not been disabled.

There are two coils inside the choke solenoid. There is a thermal switch in the cylinder block. When the motor is cold, the thermal switch activates one of the solenoid coils, partially closing the choke. When you operate the choke switch by the key, you activate the other coil. Therefor, when the motor is cold, you activate one coil and the thermal switch activates the other coil---BOTH are activated to slam the choke shut for a cold start. When you let up on your switch, only the thermal switch is activating one coil for warm-up operation.

Once the motor gets up to a certain temperature, the thermal switch shuts off and the choke should be wide open. It might be noted here that if your cooling system thermostat is stuck open or missing, the motor will not warm up properly and the thermal switch may stay closed for an extended length of time.

OK, the manual choke: It is for emergency use, not intended to be messed with every time you use the motor. So, the hood removal is no big deal. The only emergencies that might apply would be a flooded motor, a non-functioning electric choke, or a dead battery. Yes, believe it or not, you can manually choke and rope start a motor with a dead battery. If you have the muscles.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Choke adjustment question..........

F_R has provided an excellent description of the choke system. I'd also check that thermal switch to make sure it sends the a signal to the choke solenoid to open the choke fully when warmed up. I don't remember exactly the "warmup" temp which should signal the choke solenoid to open automatically, but is it pretty low, maybe 70-80 degrees farenheit.
 

mrcj001

Petty Officer 1st Class
Joined
Jul 25, 2008
Messages
313
Re: Choke adjustment question..........

Great explanation...... it all makes since to me now.

I remember when a I got the boat I read about the choke seleniod problem and I disabled the warm up circut..... I believe I have the choke mis-adjusted.

When it stalled on me I pulled the cover and the choke plates were almost closed. I didnt think that was right.

I rebuilt the carbs over the weekend and I noticed that the choke plates would follow the throttle travel. (at idle, the plates were almost closed and at WOT, the plates were almost wide open) Then when I return the throttle back to idle, the plates would want to close.

I will reajust the choke linkage.

Thanks...
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Choke adjustment question..........

Great explanation...... it all makes since to me now.

I remember when a I got the boat I read about the choke seleniod problem and I disabled the warm up circut..... I believe I have the choke mis-adjusted.

When it stalled on me I pulled the cover and the choke plates were almost closed. I didnt think that was right.

I rebuilt the carbs over the weekend and I noticed that the choke plates would follow the throttle travel. (at idle, the plates were almost closed and at WOT, the plates were almost wide open) Then when I return the throttle back to idle, the plates would want to close.

I will reajust the choke linkage.

Thanks...

It does sound like an adjustment thing. BTW, when in warmup mode, the choke plates suck open at high speed by design.
 
Top