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Old 09 December 2003, 05:33   #1
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lost power

I was out on Sunday and half way through the day, and in the middle of the Corryvreckan, when my outboard lost 1500 revs of power and decided to only run at 4000rpm no mater what I did. I am checking the fuel system first and have checked the pump, internal filter and intend to clean out the carbs tonight and change the transom filter but I have a transom mounted filter/water seperator which i thought would stop fuel contamination issues anyway.
Are there any other likely candidates to look at, it starts fine and runs fine, just won't go over 4000rpm suddenly.
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Old 09 December 2003, 06:55   #2
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Bear
check the oil levels, I once had similar problem oil level sensor not happy thought a half full oil resevoir was empty when it was half full.
Good luck
Jelly
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Old 09 December 2003, 07:36   #3
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What engine is it.

It could be one of the connecters on a fuel pipe. If their is air getting into the pipe somwhere that would cause a loss of reves at full throttle. It could equaly be that their is dirt in a filter of pipe joint. A ruck in one of the rubber pipes where the conecter has been put on ect. My best advise would be to try the engine with a different clean deck tank and fuel line straight to the engine, then the otherside of the fuel filter. This will determin if the problem in in the engine, the fuel filter or the pipes/ tank.

Have fun

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Old 09 December 2003, 09:34   #4
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Still checking

The engine is a 60hp Yamaha. I have checked the engine fuel system including all the pumps etc. Intend to chuck it all together again tonight. I thought when oil levels where low the engine ran at low speed? It is still doing 4000rpm and dropped during a run so I am assuming something has broken down, blocked or burst.
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Old 09 December 2003, 14:27   #5
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I had an Optimax that did just this, it turned out that it was an ht lead cap had worn a whole in it and was arching out against the block. I would imagine that if the engine is running at such an acurate loss then a cylinda is ot firing for some reason.

First check to make sure all cylinders are firing
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Old 09 December 2003, 15:17   #6
DJL
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Have a look at this thread. Sounds like a similar problem.

http://rib.net/forum/showthread.php?...0&pagenumber=1
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Old 10 December 2003, 10:30   #7
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I had a 60hp and had the same fault, it was water in the bottom carb, also check each coil. Good luck
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Old 13 December 2003, 14:45   #8
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The main suspect at the moment is the oil sensor as above. I stripped and cleaned and set the entire fuel system, changed the plugs and checked all electrical connections then took it out for a run. Ran fine for 30mins then the fault came back. Stopped motor and topped up half empty oil tank and it then went like a rocket when started again.
So while I am not yet 100% convinced that this is the answer it is certainly a prime suspect. Will let tank half empty again and if it returns then great, I know what it was. If not then it must be ignition related.
The local Yamaha dealer says there is no way it can be this but I am reserving judgment so far..............
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Old 13 December 2003, 17:00   #9
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This oil tank does it have a sensor to warn when the oil is getting low, brass tube with brass slidie widget on it? if so is the widget on the right way round. It has a magnet in one end and if its on upside down will fool the system into thinking its out of oil and cut the revs,

Just a thought, and don't ask me how i know just that it cost us first place in a rib race one year.

Pete

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Old 14 December 2003, 10:18   #10
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Exactly the same symptoms on my Suzuki on its first run this season. The problem was the filter in the oil flow sensor, not the level sensor. If water/condensation has entered the oil supply container, it forms a gluey mass in the system blocking the filters. There is usually one at the bottom of the oil bottle and one in the flow sensor.

The cure is to first remove the oil bottle, then remove your wifes stockings. Have a quick one and then strain the oil through the stockings into a container and if condensation is present, you will have a globby residue in the stockings. The filter in the oil flow sensor needs to be removed and cleaned with care. My local Suzuki dealer doesn't sell the filters separately. You have to buy the complete sensor at 35. The oil pump will need to be bled after reassembly of the sensor.

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