Outboard problem - any thoughts

[John the kiwi]

My own experience with a 90 s vintage honda outboard could be useful.
A real b* to start but once running would keep running. spark seemed ok, fuel seemed ok.

correct spark plugs correctly gapped obviously.
Fuel clean and clean fuel filter - obviously

I dismantled the carb and cleaned and rebuilt - no change
I bought and replaced the complete wiring loom. - no change

Finally i bought a new CDI ignition unit. Now these are sealed and have a waterproof multi-pin connector which appeared to be in good nick.
No user serviceable parts inside, cant go wrong, but if they do it will be complete failure - or so the popular wisdom has it.
Wrong!!!!!

New CDI unit. Motor instantly restored to usability.
2 years later still good.
Good luck

 

[PITCAIRN]

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.

I am prepared to cut the wires to the kill switch, I just wanted to get there after talking it through on the forum, rather than rushing and ballsing it up. I was not sure even 24 hours ago how the switch worked, now I know when its pushed in it connects both CDI units but I still dont understand why it works just by connecting the CDI units.

Also I think I have said , that when I test the spark plugs I have always got a good spark. At no time has there been nil spark when I have tested them, if the kill switch had been stuck in the 'closed' position, at some point I would have noticed 'nil' spark .

Given that fact, I came back to thinking about a problem with flooding.

However, as the story has unfolded , and I have had such helpful and good ideas from various contributors, so its been interesting to discuss/explore different avenues, the one thing I still really want to do is carry out a compression test, but I dont have a gauge. I was planning to buy one. A useful tool to have in the box anyway.

 

[Cliveshep]

Two points here - a failing CDI unit can maybe give enough of a spark to start a cold engine, and when running get enough spark to maintain running as the mag is spinning up faster than when you pull the cord, but when it is warm the slower rotation of a pull-cord start may not give a hefty enough spark, likewise the mag or ignition coil may when warm not produce enough to allow the CDI unit to operate properly.

The other is fuel has vaporised in the system or warm metal in the carb float valve has expanded stopping the needle dropping and allowing fuel to get in?

I don't subscribe to kill switch faults as you state you have always got a spark. I assume a nice "fat" blue one?

You need one of those cheap spark testers that give you a visual indication in a glass tube to be sure of the strength.

 

[PITCAIRN]

Thanks for all those contributions. My plans to tackle the engine again yesterday went to pot. My dad fell, broke both his legs !.....how does one do that !!....he blacked out , at some point came to , dragged himself down the corridor and reached a phone to call 999. he was on his own, 87yrs old, mum was away in Italy (my sister had only left the house an hour before).
Anyway was up travelling all night, planes and cars, to get to the hospital. I cant see myself back home for a few weeks , so no more boaty stuff for a while. I will repost when I can . Cheers to all.

 

[lexi]

Horrible that with Dad. Very serious and painfull.
I was next to a 33 yr old chap who broke both legs jumping off a 2ft wall, following his children.

I have stripped and worked on lots of engines. One engine I had on here I could not fix. I had new coils, boiled carbs the lot. Scope on boat told us nothing.
I sold it on Ebay with fault declared. It was a 3yr fault that. Passed a boat on Lomond and recognised the engine and bloke that bought it.
" How is engine going?" " All good, no problems" he replied. I could not believe it? I actually had to explain to the guys why not to put oil in the petrol of a Honda, before they went away!

Small outboards are simple, but they can be a nightmare, the longer the fault persists. No cause without reason. If that reason is something sisnister like a stator or exiter coil, they are murder. Keep testing till you are sick of it I suppose.

 

[VicS]

Also I think I have said , that when I test the spark plugs I have always got a good spark. At no time has there been nil spark when I have tested them, if the kill switch had been stuck in the 'closed' position, at some point I would have noticed 'nil' spark .

I had not realised that. If you always get a good spark when tested yet it still does not start then I agree Kill switch is not likely to be the problem.
BUT
Are you always getting good sparks ..... good blue ones that will jump best part of a centimetre. Not interested in little ones that jump across a plug when removed.

 

[skipper681]

Good luck Pitcairn, family will always come first. Look after your father.