Maiden voyage .... Big thanks to Cheshire fire and rescue

[Fenlander]

Could it be a problem with the kill cord wiring shorted somewhere?

[willk]

Originally Posted by thestig1973

Is it likely to be something more serious (e.g. CDI unit)

All I can say is that one of the three times I've been towed was due to a failed CDI/EMM on an Evinrude.

[thestig1973]

Originally Posted by Fenlander

Could it be a problem with the kill cord wiring shorted somewhere?

I don't think so Fenlander, my outboard had an aftermarket kill switch fitted (which I'm not keen on) so I have removed it and re wired the original switch tonight

I'm unsure if the kill switch makes or breaks the circuit to test it

[thestig1973]

Originally Posted by willk

All I can say is that one of the three times I've been towed was due to a failed CDI/EMM on an Evinrude.

Sounds expensive 😳😳🙄

[willk]

Originally Posted by thestig1973

I'm unsure if the kill switch makes or breaks the circuit to test it

Try both - one won't work - one should?

[willk]

Originally Posted by thestig1973

Sounds expensive ������

Yeah. I thought the first one was expensive. The second one felt like a limb being amputated...

[thestig1973]

Originally Posted by willk

Try both - one won't work - one should?

I know how to remove (unearth)
The kill switch, do I just short it out with a piece of wire to check the other way?

[Poly]

Originally Posted by thestig1973

I have just had had a quick look at the engine, it seems that fuel is getting through as engine is flooding after trying to start a few times. Removed spark plugs but can't find a spark on either plug/coil
How likely is it that both ignition coils have malfunctioned simultaneously?
Is it likely to be something more serious (e.g. CDI unit)

Whilst not impossible I would say it is unlikely, and unlucky if that is the fault. As soon as I read that I immediately thought it was much more likely to be an issue with the kill/stop circuit.

Originally Posted by thestig1973

I don't think so Fenlander, my outboard had an aftermarket kill switch fitted (which I'm not keen on) so I have removed it and re wired the original switch tonight

I'm unsure if the kill switch makes or breaks the circuit to test it

The normal arrangement is that when you pull the cord the switch closes making a connection between ground and the kill wire (thus shorting out the spark circuit).

Originally Posted by thestig1973

I know how to remove (unearth)
The kill switch, do I just short it out with a piece of wire to check the other way?

You can do - but that should not solve the problem (unless there is something odd going on). It might be worth looking at a wiring diagram - other circuits can intentionally short the engine, e.g. the key turned to stop (on a remote - guess you don't have one - but do you have a wiring loom that a remote could connect to?), look for any other fraid or melted wires that might be shorting, check for any odd dangling wires.

I know on mine if you blow the master fuse nothing happens - I can't recall if that applies to pull start too...

[thestig1973]

Originally Posted by Poly

Whilst not impossible I would say it is unlikely, and unlucky if that is the fault. As soon as I read that I immediately thought it was much more likely to be an issue with the kill/stop circuit.







The normal arrangement is that when you pull the cord the switch closes making a connection between ground and the kill wire (thus shorting out the spark circuit).







You can do - but that should not solve the problem (unless there is something odd going on). It might be worth looking at a wiring diagram - other circuits can intentionally short the engine, e.g. the key turned to stop (on a remote - guess you don't have one - but do you have a wiring loom that a remote could connect to?), look for any other fraid or melted wires that might be shorting, check for any odd dangling wires.



I know on mine if you blow the master fuse nothing happens - I can't recall if that applies to pull start too...

Good info, thanks poly 👍

I think my next step is to look for loose/frayed wires, and eliminate the kill switch

From the factory this outboard had a kill switch for the kill cord and also a kill switch on the tiller, a previous owner added an aftermarket switch too

Tonight I rewired the original switch, removed the aftermarket one however I still haven't ruled out the tiller kill switch

Also I need to find if I have a main fuse

I will be a happy man if it's just something simple 😀

[Fenlander]

I agree with Willk... and Poly.. ha ha.

The main ign unit could be at fault and failure will shut an engine down dead... but in general these units are exceptionally reliable across all small engines. If they do fail it is often due to an external cause that is coincidentally resolved when the replacement unit is fitted so the true cause went undetected.

With diagnostics the very first area I would double check is where there has been recent work... i.e. your stop wiring. Remember it's not just the switch to test but anywhere the black/yellow (90% sure this is your colour) power wire could be accidentally earthed (yes yours is earth to stop) might be the problem.

If you look at the service manual Boatinfo - Mercury Service Manual for 6-8-9,9-10-15 hp page 57 of 260 (or 2A-8) onwards gives the expected readings for the ign system that can be checked with a basic multimeter.

Note I know this manual covered my 2000-on Mariner/Mercury 15s but just check it applies to yours. If you find the wire colours mentioned above I'm guessing it will be the right info.

[ShinyShoe]

I'm confused why someone added a third stop switch, which is what I am reading. That says to me the factory fit one is dead!?

A continuity meter across the terminals of the switches should confirm if they change when switched. As poly says convention on most petrol engines is that with the kill cord pulled the switch is closed shorting the spark circuit to earth. Simply disconnecting that switch wire should have the effect of stopping the short.

[thestig1973]

Originally Posted by Fenlander

I agree with Willk... and Poly.. ha ha.

The main ign unit could be at fault... but in general these units are exceptionally reliable across all small engines. If they do fail it is often due to an external cause that is coincidentally resolved when the replacement unit is fitted so the true cause went undetected.

With diagnostics the very first area I would double check is where there has been recent work... i.e. your stop wiring. Remember it's not just the switch to test but anywhere the black/yellow (90% sure this is your colour) power wire could be accidentally earthed (yes yours is earth to stop) might be the problem.

If you look at the service manual Boatinfo - Mercury Service Manual for 6-8-9,9-10-15 hp page 57 of 260 (or 2A-8) onwards gives the expected readings for the ign system that can be checked with a basic multimeter.

Note I know this manual covered my 2000-on Mariner/Mercury 15s but just chech it applies to yours. If you find the wire colours mentioned above I'm guessing it will be the right info.

Very helpful as per usual Fenlander

Your right, the wire is black/yellow

I will check this tomorrow, the way the engine died was just as though I'd pulled the kill cord, and it ran great for a couple of hours previously

Thanks for the info..... It is appreciated

[thestig1973]

Originally Posted by ShinyShoe

I'm confused why someone added a third stop switch, which is what I am reading. That says to me the factory fit one is dead!?

A continuity meter across the terminals of the switches should confirm if they change when switched. As poly says convention on most petrol engines is that with the kill cord pulled the switch is closed shorting the spark circuit to earth. Simply disconnecting that switch wire should have the effect of stopping the short.

I was also confused by the added kill switch, I was told that a previous owner fitted it as he didn't like the standard kill cord set up

I believe the mercury switch can be set to "run" without using the cord, hence why the guy changed it

I will disconnect the earth of both tiller and cord kill switches and see if I have any success.... Also test switches if I can borrow a continuity tester

Thanks for the advice shinyshoe

[jeffstevens763@g]

I would say not impossible but unlikely make sure you have the plugs earthed properly when testing.

[thestig1973]

Originally Posted by jeffstevens763@g

I would say not impossible but unlikely make sure you have the plugs earthed properly when testing.

That is a good point jeffstevens, there's not many places to Earth the plug as per engine paint/enamel

I made sure bottom of plug was touching top of threaded part of cylinder head (only metal part I could reach as ht leads are short)

[willk]

Originally Posted by thestig1973

Also test switches if I can borrow a continuity tester

Buy Philex Pocket Digital Multimeter at Argos.co.uk - Your Online Shop for Test meters.

Get one in.

[thestig1973]

Originally Posted by willk

Buy Philex Pocket Digital Multimeter at Argos.co.uk - Your Online Shop for Test meters.

Get one in.

Wow .... Bargain

Ordered ..... Cheers Wilk

[jeffstevens763@g]

Originally Posted by thestig1973

That is a good point jeffstevens, there's not many places to Earth the plug as per engine paint/enamel

I made sure bottom of plug was touching top of threaded part of cylinder head (only metal part I could reach as ht leads are short)

you can always wrap some wire round the plug and back to a good earth point do it in bad light to see spark properly

[thestig1973]

Originally Posted by jeffstevens763@g

you can always wrap some wire round the plug and back to a good earth point do it in bad light to see spark properly

Thanks mate

[thestig1973]

Tonight I disconnected all kill switches, cleaned contacts on coils etc

I can now get one coil sparking, but, the other coil will spark if I swop the wires from the ECU to coil

So it's either a break in the wire from the ECU to one of the coils, or a dodgy ECU only powering one coil