Really basic engine questions!

[davechee]

Hi All,

First off, I apologise for my lack of knowledge and for the probably very basic questions. I am learning but not fast enough for my liking!

I have inherited an old outboard 20hp engine on the back of a 16ft boat. I can get the engine to start fine & run fine but I'm not sure if I am using it correctly, specifically around one of the switches on the engine.

The picture below shows the front of the engine, where there is an electric socket (I assume for a electric starter?), the fuel line, a space for a handle which I assume would connect to the mystery switch and then the kill button on the right.

https://ibb.co/mojEfm

The next photo shows the switch that sits behind the space, which I think links up to the carburetor?

https://ibb.co/d2Owt6

Now my initial thoughts that this switch was a choke, but if it is then it seems to be backwards as the engine only starts and runs when the switch is pushed in towards the engine (opposite to the way it looks in the picture) which would mean that if there was a handle it would be pushed in, as opposed to a choke pulled out. So my second thought is that this is a fuel line on/off switch?

And my final picture is of the whole engine, just in case this helps with my questions:

https://ibb.co/h9b5mR

So to summarise my long ramblings, I have the following questions for you experienced helpful heads:

1) Is this a choke switch or a fuel line on/off switch?
2) If it is a fuel line switch, is it normal for an outboard to have no choke?
3) The engine has Yamaha symbols all over it, and I have been told it is 20hp but there is no model numbers on it that I can find, can anyone identify it at all?

And before someone advises it, If the switch is the choke then I understand that the carb may need a deep clean if the engine runs with it on.

Many many thanks in advance of any answers,

Dave

 

[MapisM]

I can get the engine to start fine & run fine

Did you try starting and running the engine with that inside lever pushed in?
My guess is that it's rather a choke than a fuel cut, but by doing this test you can easily sort your doubt, I reckon...

 

[davechee]

Hi,

The engine only starts and run with it pushed in towards the engine, so opposite from how it appears in the picture.

Which is why I thought it might be a fuel cut, or an engine with a blocked carb!

But if it was a choke, wouldn't the choke being pulled out rather than being pushed in assist the engine in starting?

 

[[2068]]

I think that switch was once for a "kill cord".

A flexible cable attached to it with a plug, the other end of which was then attached to your leg, or arm.

You fall in the water, the switch is pulled, the engine stops, and you don't lose legs arms etc. from being run over by your own boat.

 

[davechee]

Aha! I hadn't thought of that option.

So if that's the case, is it normal for an outboard not to have a choke?

 

[MapisM]

The engine only starts and run with it pushed in towards the engine, so opposite from how it appears in the picture.

Ok, if it doesn't start and run at all when pulled out, then I fully agree with what FlowerPower just said.

 

[MapisM]

So if that's the case, is it normal for an outboard not to have a choke?

Not normal (particularly for a carburated engine), but possible.

 

[davechee]

Brilliant. Thanks for the information.

 

[spannerman]

The red switch is to kill the ignition to stop the motor, the hole next to it should have a knob which is the choke, you can see in the 2nd pic a silver lever protruding downwards below the carb, this is the operating arm for the choke which should connect to the knob that is missing. If it had an electrical socket this will be for powering lights, if it has electric start it would have two thick cables coming from the engine and a starter motor up by the flywheel.

 

[davechee]

Hi there. Thanks for the information regarding the electric socket. The two previous posters seem to think its not a choke but a kill switch for a kill cord to be attached to.. Do you disagree?

 

[spannerman]

Its a choke, if you move the silver lever forwards as it would if there was a choke knob fitted you will see it operates a flap on the carb. A kill switch is a button which is held out by the plastic key that you insert under it, when the key is removed the button retracts closing as switch which kills the ignition. There will be wiring at the back of a kill switch going to the CD box (ignition module). This is how all kill switches work on outboards, they are not mechanical in operation.

 

[Lon nan Gruagach]

Hi All,

First off, I apologise for my lack of knowledge and for the probably very basic questions. I am learning but not fast enough for my liking!

I have inherited an old outboard 20hp engine on the back of a 16ft boat. I can get the engine to start fine & run fine but I'm not sure if I am using it correctly, specifically around one of the switches on the engine.

The picture below shows the front of the engine, where there is an electric socket (I assume for a electric starter?), the fuel line, a space for a handle which I assume would connect to the mystery switch and then the kill button on the right.

https://ibb.co/mojEfm

The next photo shows the switch that sits behind the space, which I think links up to the carburetor?

https://ibb.co/d2Owt6

Now my initial thoughts that this switch was a choke, but if it is then it seems to be backwards as the engine only starts and runs when the switch is pushed in towards the engine (opposite to the way it looks in the picture) which would mean that if there was a handle it would be pushed in, as opposed to a choke pulled out. So my second thought is that this is a fuel line on/off switch?

And my final picture is of the whole engine, just in case this helps with my questions:

https://ibb.co/h9b5mR

So to summarise my long ramblings, I have the following questions for you experienced helpful heads:

1) Is this a choke switch or a fuel line on/off switch?
2) If it is a fuel line switch, is it normal for an outboard to have no choke?
3) The engine has Yamaha symbols all over it, and I have been told it is 20hp but there is no model numbers on it that I can find, can anyone identify it at all?

And before someone advises it, If the switch is the choke then I understand that the carb may need a deep clean if the engine runs with it on.

Many many thanks in advance of any answers,

Dave

its a choke and you have a mostly blocked jet. The engine only runs with the choke IN because you need that extra suck to get fuel.

 

[[2068]]

Hi there. Thanks for the information regarding the electric socket. The two previous posters seem to think its not a choke but a kill switch for a kill cord to be attached to.. Do you disagree?

I’m now thinking it is probably a choke too.
What is that small lever actually attached to?

 

[MapisM]

The two previous posters seem to think its not a choke but a kill switch for a kill cord to be attached to.

Actually, I also opted for a choke in principle, but I supported FlowerPower view after you said that the engine does not start/run with the lever pulled out, because I never came across an outboard which runs well with the choke pulled and does not run at all without it.
But if this can happen with a mostly blocked jet, as DT said, then the choke definitely makes more sense than the kill cord.

 

[davechee]

OK, So accepting that it is a choke.. I am slightly confused still. I have seen lots of posts regarding engines only running with the choke pulled out due to blocked jets, but my engine only runs with the choke pushed in?

Surely if the choke is pushed in then the choke is off, no?

Also, what are the chances of finding a replacement handle for it?

 

[Divemaster1]

I had a 20 hp Yamaha dated back to the late 70's when they had a working relationship with Mariner ... and yours look like a Mariner ... around 1978 due to the colour ... Yamaha's were blue... and this element discussed is the choke ...

Pending the ambient heat, you may not need the choke activated when starting, but choke on will kill engine pretty quick once up and running....

The leaver inside the cowling should be pushed backwards to be in the off position and pulled forwards when on ...

The outside connection is just a pull/push rod connecting to the leaver inside and could probably be found on ebay, or easily made up yoyrself as it fundamentally is just a slide on, pull/push mechanism...

 

[gordmac]

Why not take the air filter off and see which way the lever goes for on and off? There is no law that says it has to move in a particular direction particularly since it seems some of the operating mechanism is missing.

 

[BruceK]

The old outboard for my dink has two choke positions. One to prime, and, one to start and run the engine for the first couple of seconds. It will not run with the choke on after about 10 seconds where upon she will start to splutter and drop revs until the motor stalls.

 

[davechee]

Why not take the air filter off and see which way the lever goes for on and off? There is no law that says it has to move in a particular direction particularly since it seems some of the operating mechanism is missing.

I have done this.. and the handle absolutely is a choke so thanks for everyone for the replies. The engine only starts and runs when the choke has moved the choke plate to the closed position.... Does this make sense?

 

[gordmac]

It makes sense if that is the case only when the engine is cold, if you need the choke on with a hot engine you probably have a choked jet.