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Old 28 May 2003, 18:47   #1
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Outboard problems

Can some one help me please......
took the old girl out today but didn't even get on the plane because as soon as I opened the throttle, to anything past tickover, the engine seemed to misfire and would not rev past about 2800-3000 rpm. Just seemed as if it was running on two cylinders instead of three. Fuel getting to carbs ok (filter clean, hoses and pumps all good). New fuel this morning on the way to the slip. Swapped plugs over to new ones, all ok. All electrical connections seem ok. I'm thinking maybe a coil breaking down??? Or some one suggested a faulty rev limiter??? I've owned plenty of outboards before and luckily never had to tamper with any of them, until now. Has any one had a similar prblem to this and can maybe shed some light on the matter? All help greatly appreciated.
Regards
Jiz
The motor is a 1990-1992 yamaha 60hp autolube triple.
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Old 28 May 2003, 20:23   #2
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I don't know this engine but many outboards have 2 charge coil systems. One for low speed and one for high speed. A failed high speed system will give similar symptoms to the ones you are describing.

JW.
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Old 29 May 2003, 02:48   #3
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Hi Jizm

Not sure if this will help much but i recently bought a rib with a 1990 evinrude 2 stroke outboard on the back, first thing i did before taking her out was to have the engine completely serviced and checked by a marine mechanic i trust, then began sea trials and encountered exactly the same problems as you described, she'd get to a certain rev line then die away failing to get on the plain and it sounded as if it was missing.
After lots of jigging about with the carbs and removing the fuel filter from the line they were still stumped, the engine was compression tested and everything was ok, the fuel pump was stripped down again and no problems were found there and new fuel filter added but still the same problem.
In the end it turned out to be the petrol had been sitting in the bottom of the stainless steel tank for God only knows how long and had both gone bad and collected condensation, when it was emptied it smelt both bad and had about a quarter of an inch of water resting on the top, they replaced the stainless tank with a plastic can and the engine runs fine now.
So now i've a stainless steel tank that turns out not to be marine grade stainless steel which they think may have corroded inside, at the moment we are going to cut a hole in the top and take a look inside, if it can be salvaged i'll have a stainless steel panel made and bolt it over the hole with a gasket in between and replace the tank. The tank was made to fit exactly and it would be a shame and a pain to try and replace its size and shape with plastic tanks.

So not sure if this helps much as you say the petrol is fresh, are you using a plastic or steel tank? and could water be contaiminating the fuel?

Richard
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Old 29 May 2003, 03:23   #4
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Had a similar problem with a Yamaha 150. The fuel had formed minute sticky little balls in the carb. As soon as more fuel was injected into the carbs the little balls blocked the needle valves -
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Old 29 May 2003, 05:45   #5
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Charles

Interestingly it was one of the things we did when i had the problem with my engine was to soak the carb in some sort of gunk over night, i'm told there is tiny little holes in the carbs that suck in air and if they get blocked up with muck they stop the carbs functioning properly, apparently this is a common cause of engine problems and if the engines left sitting for a long period of time the problem is prevalent and gets worse.
Hey its interesting, when i got into boats i knew absolutely nothing and slowly i'm picking up all sorts of useful information about outboards, not sure its of any use though.

A while back someone suggested this site below:

http://www.iboats.com/cgi-bin/ubb/ul...ubb=forum;f=17

its a great site for picking up bits and pieces of useful information about engines and anything else to do with boats, of course you need to de code the America talk.

Richard
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Old 29 May 2003, 08:03   #6
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I agree it sounds like the carbs to me aswell. I have used a 1991 90 hp 2 stroke on a phantom that had the same problem. Old fuel had bloked the carbs and the new fuel was not clearing it.
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Old 29 May 2003, 17:10   #7
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Thanks for the response guys but after a few hours of tinkering (both in the water and out!) with the lack of a manual, and before I started buying lots of spare parts I didn't need, I decided to give it to a man that knows (with a resonable hourly rate) who promised to have it sorted for the weekend. I am thinking it is fuel/carb related, as you chaps suggest, but I used the boat 6 weeks ago with no problem at all. Prior to that it had sat for 7 months with no fuel in it at all (I always let it run out while flushing). Will let every one know what the problem was, when my RIB returns, by posting at the bottom of this thread.
thanks again
Jiz
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Old 30 May 2003, 06:13   #8
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Nice Move

Jiz mate i recon you've made the right move, these bits are so delicate that you could be messing with it for ages and ages and still not work it out, i've been told by a few old sea dogs that have a go servicing and problem solving is the biggest cause of problems with out boards especially when like me the person really has no real experience with what they are trying to achieve, ok so really we're not talking about changing a spark plug or a fuel filter but more fault finding more through trial and error rather than years and years of marine engine knowledge.

also worth remember when your up to you eye balls in oil and petrol you could be in the pub drinking beer and your man will call you when its fixed

Let us know what happens
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Old 30 May 2003, 08:24   #9
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When you are letting it run out when flushing it is possible that their is still fule it the carb. f you manualy drain the carb it will get rid of the last drop or you could let it run out and then start it again with some choke and you will find theat it will prob go again for a few seconds. I drain myn manual if it is going to be left. You can get a spary for the carbs if they are going to be left long term I forget what it is called as I don't use it.
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Old 30 May 2003, 12:47   #10
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Hey kid, you been drinkin'?

JW.
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