Outboard will not start.

[Hardley]

My old Yamaha 8hp will not start, any suggestions greatly appreciated.
I have it Service every winter and it has always been a first pull starter.
Last trip out it started Ok, ran for 10 minutes and thenswitched off.Sailed for 2 hours, then started OB,OK, ran for another 10 minutes, when I switched it off, I noticed some hot water trickling out, it stopped before I could investigate properly, but I am fairly sure it was not coming from the pee hole, but just inboard of there, it was unusual to feel hot water coming from this engine.
However an hour later it started OK,1st try as usual,5 minutes running and it suddenly stopped, never to start again.
There is fuel (2stroke) getting to the engine, I changed the plugs, could not see any spark, but then the sun was shining brightly so would have been hard to see, nothing appears to be loose and the engine turns over fast on the pull cord.

 

[Lakesailor]

To see if it will run at all try a splash of fuel directly into the carb throat (no choke) and give it a whizz.
If it won't start suspect spark. You really need to check for a spark however you can manage.

 

[thomshap]

Not sure if they have an overheat cut out but I have an 8hp 2 stroke and the cooling water outlet gets bunged up with salt so stops the water circulation, I keep a paper clip handy to clear it, tends to bloke up again a few minutes later but clears after three or four pokes.

 

[ctva]

I've got the same engine and I'g go with getting the cooling system working first. Check for blockages at both the inlet and outlet then work your way into the system and finally the impeller. If that is fine, go for the spark plug. Check for visual damage or better still get a new one. Remove it then replace the lead and touch the end to the casing while someone else pulls the cord. You will then be able to see if there is a spark. Next check the fuel system again working to see if the ful is getting into the carb. Are the jets blocked? Is the fuel old? After that, threaten it with a large hammer. Past that, I would seek professional help.

 

[Hardley]

Thanks Guys for the advice.
Cooling water had certainly been running on the previous startup, as I always check that after starting, so don't think that will be the problem.
Will give it a quick spray of Quick Start and see if it fires up, next time I go to the boat.

 

[Deefor]

Does your engine have a stator/magneto spark system?

Sounds very similar sypmtoms to my 1996 Evinrude 15. Does it turn over but won't fire? If it was fuel, I'd have thought it would cough and splutter then stop. Suden stop might be electrical.

This is how I sorted mine out. Buy a spark plug tester and check for a spark. As for the stator windings, there only needs to be one very small break in the windings to give the problem - OB warms up , stator winding "break" opens up = no spark. Engine cools down, wires come back together, engine fires.

Mine will run fine for weeks and then play up. I bought a manual for the Rude and went through all the resistance and voltage checks for the stator (aka charge coil) and found my problem.

It could also be a duff coil which are easier to check and cheaper to replace than a stator. My new stator was gonna be around £250 + fitting.

Best of luck with this one

 

[Hardley]

Problem was Float Needle Stuck.
Thanks for all your suggestions.

 

[KAL]

Problem was Float Needle Stuck.
Thanks for all your suggestions.

How did you free it up? My Yam8 is giving me a heck of a time getting the fuel through if it hasn't been started for a while. Runs fine once the fuel comes through, but it takes some big pressure from the primer bulb before there's a big 'whoosh' through of petrol. Mine's a 4 stroke BTW.

 

[Lakesailor]

I once bought a new needle valve for a 4 stroke Yamaha. £26

I've had good success by nipping the needle tip in some fine wet'n'dry (320grade or higher) and twizzling it. Just enough to remove the circular marks on the needle surface.
I know some needles have rubber tips and it shouldn't make any difference, but it has done.

 

[GrahamD]

If it has a "stop" pushbutton on the tiller handle or elsewhere, check that this is not shorting out somewhere. I had a frustrating intermittent fault with a Mariner 15 which sounds limilar to yours, and the Stop button wiring was the culprit. Once disconnected, the engine now works fine and I stop the engine by pulling the killcord

 

[Hardley]

Rubbed needle with some 1200 wet and dry, that did the trick.

 

[VicS]

Rubbed needle with some 1200 wet and dry, that did the trick.

Soft tipped needles are the ones particularly inclined to stick on their seats.

They may have a small spring clip that links them to the float arm so that the weight of the float pulls them off the seat

Worth checking that this clip is fitted .

See the diagram HERE where it is part #21

.

 

[joe17]

Google dug up this old thread for me when I was searching a similar problem with an old Yamaha 8HP. Started, ran, then stopped and wouldn't restart.

For the record my problem turned out to be the kill switch. The existing kill switch plastic tab wasn't holding the power button sufficiently out. I made a thicker one and it started immediately.

No idea why it ran OK for a few mins originally, but maybe it was vibrations and existing switch would work OK if it was in the right place?

Fun afternoon, but the feeling of satisfaction when the thing finally started was probably worth the hours of checking the plugs, fuel, desperately pulling the starter, etc.

 

[William_H]

The easist way to diagnose o/b not starting is to remove the plug after many attempts at starting. If the plug is wet with fuel you have a plug or ignition problem. Dry and clean the plug. If the plug is dry you have a fuel problem. good luck olewill

 

[joe17]

The easist way to diagnose o/b not starting is to remove the plug after many attempts at starting. If the plug is wet with fuel you have a plug or ignition problem. Dry and clean the plug. If the plug is dry you have a fuel problem. good luck olewill

Yes, I had wet plugs and a lot of fuel in the water/sea after the failed start attempts. After making sure the fuel was fresh and clean I thought it was an ignition problem.

However, this thread made me wonder if it was a needle stuck open flooding the engine. It wasn't in my case.

(Anyway, this is a 4 year old thread. I only added to it as it led me towards solving my problem. Maybe another day someone else searches for something similar and this helps them in someway)