hard to start outboard

[sawdoc]

hi folks,
i have inherited a 1997 Mariner 15hp ob which is hard to start. I have renewed fuel and plugs. Sometimes it will fire first time bit if not I have to let her sit and try again say 10 mins later. Once she starts she is a joy to use - good and powerful and easily started after that.
Any suggestions welcome!

[Clyde_Wanderer]

Assuming it has an external/remote fuel tank, check the fuel line to engine connector for air tightness, check the O ring on the inner bore of this connection.
If it is a 2stk and had lay up for quite a while it is possible that there could be Gum/Varnish in the carb which might be clogging up the low speed jets and emulsifier tube, it may need stripped down and the best way to clean these jets is to boil then in water for 1/2hr or so then blow them out and dry off.
Maybe it would be worth getting an outboard mechanic to give it the once over.
Hope this helps, C_W

[ljs]

I have been wondering if this is actually the derivation of another nautical term.
As you're sitting in the middle of the channel waiting 10 minutes to give it another pull, the skippers of passing boats are shouting at their helmsmen, 'Hard a starboard..'

PS Good luck with the outboard!

[sawdoc]

Assuming it has an external/remote fuel tank, check the fuel line to engine connector for air tightness, check the O ring on the inner bore of this connection.
If it is a 2stk and had lay up for quite a while it is possible that there could be Gum/Varnish in the carb which might be clogging up the low speed jets and emulsifier tube, it may need stripped down and the best way to clean these jets is to boil then in water for 1/2hr or so then blow them out and dry off.
Maybe it would be worth getting an outboard mechanic to give it the once over.
Hope this helps, C_W

thanks CW - think I may have to extract the carb as I also notice she won't idle easily until warm - cuts out if you reduce the revs close to idle. Have not done that before so some reading up of the manual to be done!

[Clyde_Wanderer]

Assuming it has an external/remote fuel tank, check the fuel line to engine connector for air tightness, check the O ring on the inner bore of this connection.
If it is a 2stk and had lay up for quite a while it is possible that there could be Gum/Varnish in the carb which might be clogging up the low speed jets and emulsifier tube, it may need stripped down and the best way to clean these jets is to boil then in water for 1/2hr or so then blow them out and dry off.
Maybe it would be worth getting an outboard mechanic to give it the once over.
Hope this helps, C_W

thanks CW - think I may have to extract the carb as I also notice she won't idle easily until warm - cuts out if you reduce the revs close to idle. Have not done that before so some reading up of the manual to be done!

Well in that case SD you will find the primary jets are clogged or have a coating of varnish on them which is caused by old 2stk mix allowed to dry out and the residue forms a varnish type resin.
Be careful with the emulsifier tube as the holes along its length are tiny and easy to miss in the cleaning process, dont poke them too much, better to blank one end with a finger and apply compressed air to the other and blow it out.
C_W

[ruaridhmaccallum]

Clyde_Wanderer is on the money re. low-speed jets.
However, starting OK after having been left for 10 mins. suggests flooding, as does poor idling.
If you give it full throttle and no choke will it eventually cough into life?
If you pump the priming bulb, does it continue to depress slowly even when hard, eventually causing fuel to leak out the carb?
If yes to either, then float valve is sticking, probably also because of the aforementioned varnish.
Either way you'll have to strip the carb, not a huge job.
One other thing, there is a fuel pump on these engines, probably integral to the carb but maybe separate. When they've been lying for ages the diaphragms & non-return valves can become perished and un-usable, which may also give the symptoms described. A repair kit will be required, again not difficult to fit.
Hope this helps.

[sawdoc]

Hi folks
Thanks for the advice
I'm a bit nervous - I've read the manual - the job seems straightforward enough and I intend taking a few snaps beforehand - is it easy enough put it all back together again?
We've had a gale blowing here for the last week which is putting me off working on the engine.
If I took her out for a trip at the weekend ( say half hour or so around the bay) would this clear the gummed up jets or is removal of the carb the only option?
To address Ruari's queries, I did have the bulb not going hard initially and fuel coming out of the top of the carb but that seems to be resolved now that I have got the engine running. bulb stays reasonably hard and no leaking fuel.
Even with full throttle engine won't start unless primed. Once she starts then, I push back in the priming knob and she begins to quicken her revs. However if i throttle back close to idle she will cut out. If I left her running at fairly high revs for several minutes she is less inclined to cut out when throttled back.

[ruaridhmaccallum]

To answer your questions:
Yes I would say it's easy enough to put back together again but I can't remember what it's like to have not done it before! Objectively it should be a fair enough job for the less-experienced. Only warning (apart from don't do it over the water unless you're very confident!) is to make sure you have a screwdriver that's the exact right fit when removing the float bowl or fuel pump screws, it's easy to mess up the heads which can make them a pain to get out.
In my experience running the engine for some time won't clear carb blockages especially "varnish" deposits - by all means give it a try, just don't build your hope up!
Cheers,
Ruaridh.

[sawdoc]

Ruaridh
Thanks again - incidentaly my red haired son is also Ruairí - no need to translate I'm sure!