Outboard problem - any thoughts

[VicS]

You're just bypassing the switch with another one that you know that works.As I see it it'll determine weather or not the kill switch is functional

No it wont if you just connect another one in parallel.

If the existing switch kills when closed and is sticking in the closed position putting another switch in parallel with it will tell you nothing.

Disconnecting the existing switch, by cutting the wiring if necessary, and fitting another ot just being able to short the two wires together is the way to check it out

 

[AndrewB]

My mind is turning to simple flooding issues. Maybe this is all about flooding and the carb having issues, maybe the float in the carb is not functioning correctly, maybe there is some dirt somewhere....but then why would the engine run so dam good when it eventually does get going ?

Compression ?....I need to test that, its got to be tested if only to remove it as a possibility.

What else ?

Hmmm, frustrating.

So, it starts reliably when cold, but not when hot. Choke/air issues just possibly? Maybe this is a cooling issue - is it overheating when running? Maybe a head or head gasket problem that might result in weaker compression, but only when hot?

You seem to be leaning towards a fuel supply rather than an electrical or air supply fault. Is there a fuel pump, in which case you might just have vapour-locking, when the fuel in the lines on top of the engine evaporates from the heat. It won't happen while the pump is running, only once stationary. I suppose you've checked there actually is fuel in the carb? When it fails to start, try opening the drain to check. On the other hand if it is, as you suspect, flooding, then by draining a little fuel this way you should be able to restart it after a few pulls.

 

[Beyondhelp]

Carb vapor lock perhaps?

Get a can of easy start... spray it down the carb when it is having one of its moments and see if it then coughs/starts. If so, its simply a fuel issue... -which is what I think it is anyway.

 

[30boat]

No it wont if you just connect another one in parallel.

If the existing switch kills when closed and is sticking in the closed position putting another switch in parallel with it will tell you nothing.

Disconnecting the existing switch, by cutting the wiring if necessary, and fitting another ot just being able to short the two wires together is the way to check it out

As a last resort then, just cut the wires to the kill switch.They can be resoldered back and insulated with heatshrink if the problem doesn't lie there.Or cut only one of the wires.That'll do it.

 

[Lakesailor]

I'll take it off you hands for £25. Save all the worry.

 

[cliff]

I'll take it off you hands for £25. Save all the worry.

£30 - any advance on £30?

 

[PITCAIRN]

As a last resort then, just cut the wires to the kill switch.They can be resoldered back and insulated with heatshrink if the problem doesn't lie there.Or cut only one of the wires.That'll do it.

Just wondering how the kill switch actually operates to 'kill' the engine.....what actually is happening electrically when one operates the switch....also, when one pushes the switch in is one 'closing' or 'opening' the switch, i.e. pushing in is connecting or disconnecting ?....and connecting / disconnecting what exactly ?

Clearly I need to understand whats happening before cutting any wire since the action of 'cutting' the wire may in fact be electrically 'disconnecting' which may be exactly what the switch is there to do, i.e. 'disconnect' thereby killing the engine.

 

[30boat]

Just wondering how the kill switch actually operates to 'kill' the engine.....what actually is happening electrically when one operates the switch....also, when one pushes the switch in is one 'closing' or 'opening' the switch, i.e. pushing in is connecting or disconnecting ?....and connecting / disconnecting what exactly ?

Clearly I need to understand whats happening before cutting any wire since the action of 'cutting' the wire may in fact be electrically 'disconnecting' which may be exactly what the switch is there to do, i.e. 'disconnect' thereby killing the engine.

On a magneto (points) ignition the kill switch earths the generating coil which cuts the sparks.on a CDI I don't know ,perhaps it cuts the power supply to the unit.That's how it worked on the electronic ignition on my old Triumph Trident.

 

[PITCAIRN]

Some pics of the motor.

 

[30boat]

Some pics of the motor.

You'll have to try again,no pics I'm afraid.

 

[PITCAIRN]

View attachment 42468View attachment 42467View attachment 42469View attachment 42470View attachment 42471View attachment 42472View attachment 42473View attachment 42474View attachment 42475

 

[PITCAIRN]

This link would seem to answer my own question , ' how does the push to stop' kill switch actually work.
http://www.duckworksmagazine.com/05/columns/max/3/free.cfm
It states that the kill switch is normally in an 'open' position, off, disconnected - when pushed in it is 'closed' i.e. connected (its on a spring of course which is why when you push you have to hold your thumb down on the switch until the engine cuts out) . When the switch is pushed in an ''electrical connection is made between the ignition points of both cylinders. This disables both cylinders and the engine stops running. One pushes the stop switch, the stop switch electrically joins the two cylinder's ignition points, and the engine stops.''
Now I am not entirely sure why connecting the two cylinders ignition points causes the cylinders to shut down, (I mean I can deduce that the spark plugs are 'switched off' so to speak as a result of this connection, so no spark - no bang, but why does the spark stop ? )

But it clearly works. The kill switch on my motor is indeed connected to each CDI unit. You can see that in the photos I have posted if you trace the wires - better photos to come, I seem to have hit my limit for now )

 

[Lakesailor]

It is talking about points systems.

Have you tried a multimeter across all those bullets connectors. Could just be a bit of corrosion.

 

[VicS]

'
Now I am not entirely sure why connecting the two cylinders ignition points causes the cylinders to shut down, (I mean I can deduce that the spark plugs are 'switched off' so to speak as a result of this connection, so no spark - no bang, but why does the spark stop ? )

Because with a two cylinder engine with points one or other set of points will be closed at any point in the cycle. If the kill switch links them the closed set will short out the opening set,.... hence no spark!

But your Yammie has a CDI system so the explanation is not valid.

 

[VicS]

It is talking about points systems.

Have you tried a multimeter across all those bullets connectors. Could just be a bit of corrosion.

I am 99% certain that the engine will be stopped when the kill switch closes. That means that corrosion on a connection would prevent it from stopping the engine rather than preventing it from starting.

 

[PITCAIRN]

It is talking about points systems.

Have you tried a multimeter across all those bullets connectors. Could just be a bit of corrosion.

The two wires running from the kill switch each connect into a separate bullet connector, which in turn connect into each separate CDI unit. So the orangy/brown coloured wire goes from the kill switch to the CDI No.1 (uppermost) and the grey/whitish wire runs from the kill switch to the other CDI, No.2 (lower).

Pushing in the kill switch will serve to connect these two CDI units - why that would prevent the spark I dont know .

I have not yet tried a multi meter on the various connections made at those bullet connectors because the connectors are sealed. I dont want at this stage to cut into anything until I have thought it all through/discussed, and know what I am trying to achieve .

(excuse the laboured explanation above, but just want clarity that we all talking about the same items, cheers)

 

[PITCAIRN]

I am 99% certain that the engine will be stopped when the kill switch closes. That means that corrosion on a connection would prevent it from stopping the engine rather than preventing it from starting.

Correct, pushing in the kill switch (closing - connecting) does stop the engine. If anything by way of corrosion is at work, then its corrosion on the spring inside the kill switch, preventing the switch returning to an 'open' position.

Thanks to all for their input thus far. I am back at the boat Wednesday so will keep on it at that time and report progress.

 

[Lakesailor]

You both misunderstand what I am saying. I am not concerned with the stop switch. There seem to be other bullet connectors. If some are in the line from the trigger unit to the CDI it could be that they are offering intermittent connection. At this stage it's worth checking everything.
You don't need to disconnect the bullets. That would disguise the symptoms anyway. The probes should be able to penetrate the wire insulation.

 

[VicS]

You both misunderstand what I am saying. I am not concerned with the stop switch. There seem to be other bullet connectors. If some are in the line from the trigger unit to the CDI it could be that they are offering intermittent connection. At this stage it's worth checking everything.
You don't need to disconnect the bullets. That would disguise the symptoms anyway. The probes should be able to penetrate the wire insulation.

I cant help thinking that if the trouble was caused by bad connections it would be more random and erratic. Maybe I am wrong but I get the impression that when it does start it will run ( and idle ?) perfectly indefinitely, not run for x or y minutes then conk out.

If that is so then its difficult to imagine any fault with the ignition system or with the fuel and carburation.

The trouble always seems to be that it often wont start again after being stopped on the button.

 

[Lakesailor]

But any problem with non-starting could be blamed on the stop button as you will always use the button prior to the next starting attempt (unless it conked).

It could still be the button and snipping the wires is the first step to isolating it. If the OP isn't willing to do that, he may as well flog it and buy a newer motor. Otherwise it could take weeks to find the problem, and it could still be the button.