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Old 28-04-2016, 06:23 PM   #1
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125hp 2-stroke Mercury 1998 skipping a beat

I winterise my engine each year but still start it up and warm up the engine every month.

I just dropped it in the sea for the first time since October, added fuel system cleaner to the correct ratio.

Motor runs fine, after an hour of running at 3000rpm I upped it following my old school of thought relating to an engine needed WOT to give it a good clean out every once in a while.

At 90% it runs with no problem. At 100% you get an initial boost but then the engine started to give in a bit and I could hear it wavering, dropping down and picking up in revs. Overall at 100% we were going 2-3mph slower than at 90% despite an initial surge.

Dropping back down to 90% and the symptoms disappear.

Any ideas? Could the fuel filter need a clean? Or could this be a bigger/other issue?
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Old 28-04-2016, 06:43 PM   #2
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When it happens get someone to squeeze the priming bulb and see if it improves.
Or bump the choke momentarily..
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Old 28-04-2016, 07:34 PM   #3
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When was the fuel pump last rebuilt,if not for a couple of seasons i would get a service kit and try that
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Old 30-04-2016, 03:43 PM   #4
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Cheers for the replies. I went out today and the problem didn't resurface (which makes me think it is the fuel filter - in which case do I simply replace it?). I've lost a little on the top end (5% or so), but no more choking. I tried the choke at speed and it seemed to cut power all together until I released the choke.

I haven't rebuilt anything in the past 2 years. Just a service each year which I do myself as per the manual. I do about 20-25 hours a year.
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Old 30-04-2016, 05:26 PM   #5
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fuel only has a shelf of 6 months if not treated, after that it breaks down and can leave a gel behind which can block jets in the card etc. I would strip and ultra sonic clean them.
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Old 30-04-2016, 05:28 PM   #6
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this will stop if from happening

https://www.quicksilver-products.com...ems/additives/
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Old 30-04-2016, 10:18 PM   #7
oxo
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filter

swap out the water separating fuel filter first! I've rebuilt carbs time after time only to find out I've made that schoolboy error!
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Old 01-05-2016, 02:57 PM   #8
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Great, thanks. I will do both of the above.

I've been servicing my engine with generic alternatives to the suggested quicksilver products since in Greece it is almost impossible to find quicksilver products at the moment. I've noticed the chemical make up of the various greases and oils are not the same as the quicksilver ones.

I'm going to start posting them over from the UK I think.
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Old 01-05-2016, 05:42 PM   #9
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Quote:
Originally Posted by oxo View Post
swap out the water separating fuel filter first! I've rebuilt carbs time after time only to find out I've made that schoolboy error!
Yes school boy error would of not been changing the filter first. Always work from the fuel tank, fuel lines, Fuel filters, connections etc working your way to towards the engine until you get to the pump and carbs etc.

Costumers engines not so much (as the dont like paying for it) but on my own engines i strip and ultra sonic clean the carbs every years as if its an service item. Doesn't take long and its peace of mind knowing its been done!

We would be help to ship quicksilver stuff to you if u so wanted!

Hope this all helps.
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Old 08-07-2016, 08:21 PM   #10
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Got all this done. You don't even want to know how I replaced the fuel filter (base had been bolted with non stainless bolts that had rusted right through).

I've clawed back 2 of my lost 5 mph on the top end. I'll do an ultra sonic clean before next season. Thanks for all the advice!
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