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Old 06 July 2014, 02:33   #11
Country: UK - England
Town: Sussex
Boat name: Bombard, Y-162
Make: Aerotec 380, Y-Class
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 2,784
Thanks for input guys but just to clarify:

1. Engine is minty and fully serviced to the letter by me after purchase it and it ran perfectly on two fairly long sea days throughout after this (new NGK plugs, gear oil, fuel system/tank clean, gear oil, impellor etc, etc). Only done about 8 - 10 hrs since the service then.

2. No issues with fuel line, bulb, vent etc - as I say it runs fine with throttle held open (conclusion that non-idle circuit fuel suply and plugs etc cannot be an issue) just will not start without throttle held open or idle. Very on/off - ie it won't even cough or splutter/start on idle.

3. After last sea day it was fine when flushing.

Odd thing is coming back three weeks later you might expect it to cough splutter or run erratically but as above it just will not run full stop - leads me to believe it must have gummed up in the idle jet or something despite running dry and stabaliser? ie nothing has 'broken' just sitting there?

As I say fuel was decent with stabaliser added right away.

Anyone stripped one of the carbs in these and can help out with clues - has to be a carb issue surely.

Coming across as Mr Grumpy but 100% totally pi$$ed off with this - boat engines are now in my experience so unreliable if despite all the above (ie looking after them perfectly) they still let you down in this way just because they have sat there for three weeks. And after the first time it lets you down you never have the same confidence again especially when going to sea...

Originally Posted by uncle al View Post
It sounds like fuel trouble, will it tick over and run ok if pressure is kept on the primer bulb? If it does I would want to fit a fuel pump repair kit,if it doesnt see some suggestions below.
1/ is it old stale fuel?


if so remove strip clean the carbureter re-assemble and refit.
2/ has it been serviced recently?

Yes, see above.

3/ are the correct spark plugs fitted as per parts book?


4/ is the obm set up correctly as per chapter on settings for timing and carburation?

5/ are the compressions ok?

4+5 - not checked other than idle speed but ran perfectly for 8 hours or so before 'laying up' (!) for three weeks.
good luck

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Old 06 July 2014, 05:54   #12
Country: UK - England
Town: Dorset & Hants
Boat name: Streaker/Orange
Make: Avon/Ribcraft
Length: 4m +
Engine: 50Yam/25 Mariner
Join Date: Apr 2007
Posts: 5,551
You have my sympathy with the problems, I'd guess it is however something simple like a blocked carb idle jet.?

All the posts remind me why i splashed out on a new efi engine recently. What price the knowledge it well start and go on the button every time? In its lifetime it will pay for itself on fuel saving, but appreciate I'm lucky to be able to do this.

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Old 06 July 2014, 06:42   #13
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,283
I suppose Peter has a point. Not only are you comparing 2 stroke with 4 stroke you are comparing mechanical to electronic managed engines..

My first cars were mechanical with points etc. seem to remember opening the bonnet a lot on them! My modern car is computer controlled which does seem to mean when I turn the key it kicks into life and goes... but i also know when the dreaded orange light comes on its gonna cost me 80 to find out whats wrong and usually a whole load more to fix it. The Mrs's car did this the other week... quote for fix is 600... the fault wouldn't exist on a non-computer controlled engine and would drive just fine...

So my conclusion is that computerised engines are probably lots more reliable but when they fail will be beyond most people to fix and will usually cost a fortune to fix. Your old croaky mechanical engine is maybe less reliable but fixing it will probably cost less than the diagnosis for the computerised one!!
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Old 06 July 2014, 08:11   #14
Country: UK - N Ireland
Length: 6m +
Join Date: Oct 2013
Posts: 28
Must be so frustrating!! My story will make you feel even worse. The rib i had bought hadnt seen water for 6 years!!! didnt drain the fuel, just topped up with fresh stuff. It started on the first cylinder, couldnt believe it!! It "hunted" a bit for the first 5 mins at planing speed but after tht it ran perfect. Had my first outing in her since i bought her a year ago, the first turn n off it went. Only niggle was a blocked tell tale which was easy fixed. Over the moon with it
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Old 06 July 2014, 08:44   #15
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Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,390
Know how you feel. Had a similar issue with a poor running Twatsoo. Turned out to be timing was out and carbs needed synchronised.

Back to your problem. Are you definitely getting a spark. Might only be running on one cylinder. Pull the plugs, clean and re-gap. Get someone to hold the spark plug with the HT lead connected against the outboard head, and pull to turn it over. Do this with both spark plugs to ensure you're actually getting a spark. Sometimes the HT connection can be loose or it's not making contact with the spark plug properly.

Next carbs. Before stripping down, loosen the drain plug and look at the fuel colour. If there's sediment, then I'd go for a carb strip down.

Also ensure choke is out, tank is vented and put the throttle past 'start'. Make sure stop lanyard is connected, etc.

Under the cowl, check all electrical bullet connectors. Had a Mariner 4hp that wouldn't start because I'd accidentally pulled an earth cable.
Is that with or without VAT?
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Old 06 July 2014, 10:12   #16
Country: UK - England
Town: bicester
Length: no boat
Engine: outboard only
Join Date: Feb 2009
Posts: 913
If you are sure that the fuel system is ok then we sorry need to look at the electrics.
1/any wires pulled out that you can see?
2/have you dis-connected the kill wires, if you have does it run?
3/If it runs with the kill wires diconnected are all the earth wires crimped firmly to the wires and are the earth connections clean and tight?
4/ If all the above are correct you need to do a voltage check on the switch box ,stator and trigger. I always tested voltages never the resistances.
This should have been number one have you done a spark check at the spark plugs, I dont mean lay a spark plug in the btm tray and watch it spark, you should use a spark checker that has a nice big gap that really makes the ingintion system work hard.
Be careful spark checking is dangerous (open spark plug holes that have fuel/air mix coming out when pulled over)
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Old 06 July 2014, 13:18   #17
henryfreston's Avatar
Country: UK - England
Town: Thornbury
Make: Avon Searider 4m
Length: 4m +
Engine: 50hp tohatsu tldi
Join Date: Sep 2012
Posts: 648
First port of call for me would be cleaning the carb, it's just another thing to tick off.

The jets are so bloody tiny that even a grain of sand can get lodged in there and prevent it from running 100%.

Check out some youtube videos on outboard carb cleaning if you haven't done it before.
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Old 06 July 2014, 13:41   #18
bingosucks's Avatar
Country: UK - England
Town: Nuneaton
Boat name: gnasher
Make: sr5.4
Length: 5m +
Engine: hidea 5 yam 90
Join Date: Oct 2011
Posts: 549
Lmao i reccon carbs outcof interest im just learning you can set the carbs up as per instructions but they dont want to work for no logical reason . I watched a video of someone set a vacuum gauge on a carb this is the only way to tune it correctly as im guessing now theres an element of wear this catches a lot of very good mechanics ou
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Old 06 July 2014, 14:12   #19
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Country: UK - England
Town: The wilds of Wiltshire
Boat name: WhiteNoise/Dominator
Make: Ballistic 7.8/SR5.4
Length: 7m +
Engine: Opti 225/Yam 85
MMSI: 235090687/235055163
Join Date: Jul 2005
Posts: 12,691
Take notice of Uncle Al.Ignore everything else that's been said so far .

It's unlikely to be carbs unless you've either got water in them or flooded it on 1st pull and kept trying to start it on full choke. The hot weather could mean you need to use no choke.
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Old 06 July 2014, 14:14   #20
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Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 13,093
Originally Posted by Nos4r2 View Post
The hot weather could mean you need to use no choke.
I seem to recall he did that with his old 9.8 - Doubt he did it again

"Who knows what evil lurks in the hearts of men?"
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