Outboard problem - any thoughts

[PITCAIRN]

The outboard is a Yamaha 8hp, about 1985/6 vintage.
Sometimes when I have not used it for a few days, it starts and runs fine, like today, ran it for 20 mins no problems, motored about, full throttle, it was fine - but then when I return to the jetty and have left the engine switched off for say an hour, when I return the engine wont start, nothing, no coughing, no spluttering, absolutely dead, I pull the pull cord and get no response whatsoever.

I have replaced the spark plugs, cleaned the carb, changed the fuel. I still get the same problem, I am leaving it overnight, tomorrow it will probably run, but when I turn it off - go away and then return some time later, I bet its dead again.

What is going on ?

 

[No Regrets]

'Dead' to that extent would suggest electrics?

Assuming it has two coils, forget those, as one would work wouldn't it.

Plugs, same again.

Fuel pump? (not elect I know...LOL) Tried pumping fuel bulb first?

Ignition switch?


Do you have a spark when trying to start it? Pull a plug lead off, and stick any old plug in, earth the plug and see if it sparks. If not, you know where to go, if it DOES spark, then it will almost certainly be fuel.


Unless it's a flooding carb, due to float issues?

 

[VicS]

Check for sparks is the first step i think.

check stop switch.... try disconnecting it if its easy to do

 

[PITCAIRN]

Thanks for those two replies. I agree, my thoughts were 'electrics', I am going to check the spark plugs tomorrow, but why would they work fine for the 20 minute run about I did this morning, but then after a pause of an hour or so, not work....and this has happened more than once... Engine runs on first attempt of the day, but then wont restart some time later. As I say in my post, I bet when I first try to start her tomorrow, she will run.

 

[VicS]

Thanks for those two replies. I agree, my thoughts were 'electrics', I am going to check the spark plugs tomorrow, but why would they work fine for the 20 minute run about I did this morning, but then after a pause of an hour or so, not work....and this has happened more than once... Engine runs on first attempt of the day, but then wont restart some time later. As I say in my post, I bet when I first try to start her tomorrow, she will run.

Really why I suggest checking the stop button. Pressing that is about the only thing you have done between running perfectly and not running at all.

Sticking a bit perhaps but has released by the next day.

Dunno ??? I'd look at it 'cos I can't think of anything else!

 

[PITCAIRN]

Yep I agree, will check the button stop, it also sounds a possibility.

 

[Lakesailor]

'Dead' to that extent would suggest electrics?

Assuming it has two coils, forget those, as one would work wouldn't it.

Dangerous http://www.ebay.com/itm/6G1-85570-0...D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

 

[Alex_Blackwood]

Really why I suggest checking the stop button. Pressing that is about the only thing you have done between running perfectly and not running at all.

Sticking a bit perhaps but has released by the next day.

Dunno ??? I'd look at it 'cos I can't think of anything else!

+ 1 for stop button. Had a similar problem, albeit with different engine, "jiggled" the stop button a few times. Problem solved.

 

[mtb]

have you told it off some times these out boards are just so naughty

 

[PITCAIRN]

Well today was the day of reckoning, ME v. OUTBOARD. This was going to be a tussle to the death !
The first thing I did was check for spark....yes a nice strong spark from both plugs.
Next I took a look at the kill switch, a simple on/off push switch, BUT as I discovered , its totally sealed, no access to the actual moving parts, and the wires are all sealed into the switch, and sealed into connections at the coils. So I just worked the switch pushed in and out feeling for a positive click each time .

I took the engine to the water and pulled the pull cord - NOTHING ! not a wimper, I pulled again , nothing, I did a complete spark plug test again. I had a good spark ....I pushed the kill switch a few more times.

I sat and stared at the damned thing for 10 minutes. What on earth could the problem be. I literally said I'll try one more go then I am throwing this engine into the dam sea.....................IT STARTED !.....I ran it for about 20 minutes, went for a cruise around the marina, came back to base, pushed the kill switch, started it again, turned it all off, started again, hit the kill switch again, went off for a pace up and down the pontoon, came back , it started again, and again and again.

WTF !!!

 

[fisherman]

With my Yam 8B, bit older than yours, the water jacket had rotted out, but that showed a reluctance to turn over as it hydraulicked.

 

[Lakesailor]

WTF !!!

Stick it on eBay and get a newer, more reliable motor.
Unless you can find something wrong and fix it you will never have confidence in that motor.

 

[VicS]

WTF !!!

Kill switch ......gotta be.

Somewhere you can disconnect the wiring 'cos the switch is available as a replacement part

 

[NickRobinson]

I'm going get flamed but..... the tank vent was open, wasn't it?

N

 

[explores]

You frightened it by threatening to throw it in the sea.

 

[condor]

Not a kill switch problem if you got sparks.

 

[AndrewB]

I'm going get flamed but..... the tank vent was open, wasn't it?

My first thought, too. Common reason for an engine to conk out after 10 minutes, or refuse to restart. It's just a pin-prick hole on those old Yamahas, maybe part blocked?

 

[VicS]

Not a kill switch problem if you got sparks.

when he had sparks it started.

My first thought, too. Common reason for an engine to conk out after 10 minutes, or refuse to restart. It's just a pin-prick hole on those old Yamahas, maybe part blocked?

The engine in question I am sure does not have an internal fuel tank, even as an option, only a remote tank. I am sure that if there was a fuel problem due to closed or blocked tank vent, blocked filter or other obstruction , defective pick-up from the tank etc it would be obvious that the system was not priming when "pumping the bulb".

A question for the OP though perhaps ... Does the system seem to prime properly/ normally with the bulb. You can normally feel when fuel is being pumped through and then the bulb becomes firm when the carb is full.

 

[fisherman]

A friend bought just this engine in about 1982, it gave up about 8 years ago, he took it to the local specialist who told him they were never any good.....'but you sold it to me.....'

 

[Lakesailor]

The fact that when it does start it runs well suggests the fuel side is fine.
If it were mine I would get a coil pack from ebay for a few quid and try that. It could be a faulty wire or heat soak effecting it.