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Old 21 February 2015, 12:39   #1
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Poor starting - Yamaha 30 2S, 2 Cyl

Hi,

I have an early 90's Yamaha 30 (the same '689' engine they made for Mariner).

It eventually starts if I open the throttle, close the choke and wind it over for about a minute (in ten second burst sso the starter motor doesn't get too hot). After that it runs quite happily and, if stopped, starts with a touch of the starter or pull of the cord.

I've only tried it when its running but pulling off the spark plug boot shows a spark across a gap of about 2 cm.

Any thoughts about why it is reluctant to start but runs happily after that?

Thanks

Hugh
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Old 21 February 2015, 13:26   #2
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Sounds like not enough fuel I'd see if your pilot jet is blocked I'm assuming it's a carburettor


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Old 21 February 2015, 15:18   #3
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Is your fuel bulb priming up the carb correctly? It sounds like lack of fuel but not once it's started so I have to think that the carb is not full of fuel when you first try. Failing that it's a fuel pump check and a carb clean.
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Old 21 February 2015, 16:32   #4
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When I prime it I can hear fuel going into the carb - up to the point that the bulb goes hard (the float has closed off the fuel to the bowl).

Tomorrow I'll try and start it with someone pumping the bulb.
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Old 21 February 2015, 20:01   #5
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Pull twice on the choke. If that doesn't work pull three times on it. Assuming it gives it a shot of fuel of course.

You could also take some starting fluid and give it a quick squirt.
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Old 22 February 2015, 06:37   #6
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If it's the older 30 yam, pulling twice on the choke won't help. It's not a primer like on the Mercury's. Priming fluid will ruin an engine as it washes the oil off the bore and over time causes engine wear and loss of compression. It sounds like your fuel bulb is ok. Here's what I would do.

1) Use new petrol/oil mix (the old might be rancid if it's been sitting). It's unlikely you got bad fuel from the pump, but not impossible.

2) Ensure there is no water in your tank before you refill.

3) Take off the airbox and squirt fuel right down the intake.

4) Use the normal starting procedure.

5) if it fires straight up, clean out the carb. It will certainly be a fuel issue.

I'm trusting you've not adjusted the timing or the needle on the carb!
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Old 22 February 2015, 07:14   #7
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old fuel or the choke butterfly is out of adjustment
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Old 22 February 2015, 11:26   #8
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I have the same problem in my Yamaha 115 v4. Starts fine once warmed but is a pig from cold
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Old 22 February 2015, 11:40   #9
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Sounds like they may need a compression test.
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Old 22 February 2015, 18:54   #10
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Compression tests are always good. First rule out major mechanical before messing with anything else.

Quote:
Originally Posted by RIB-Teccie View Post
Priming fluid will ruin an engine as it washes the oil off the bore and over time causes engine wear and loss of compression.
If you are referring to "starting fluid" it may cause damage over time, but a use once or twice as a diagnostic will not do any harm, unless you over use it. A single shot into each carb is all it takes.


Extra Strength Starting Fluid for the fastest starts
Starts engines quickly and reduces drain on batteries
Compatible with gasoline or diesel engines
Contains upper cylinder lubricant



It is a quick way to see if an engine is getting enough fuel. Then once diagnosed it can be properly repaired.

Does this Yamaha have "Prime Start". Do you have the owner manual? If not I recommend buying one.

Does the motor have one of these levers?



What is the year of the motor?

I used to have a Yamaha 90HP years ago. It was a fantastic engine that only failed me once when the starter bolt fell down. Put the bolt back in and it fired right up. Other than an occasional impeller, lower unit oil change, and spark plugs it never needed a single repair over 100's of hours of use.
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