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Mariner 90 HP three cylinder two atroke outboard

Roger laws

New member
I have a 90 HP three cylinder two stroke outboard. It runs extremely well up to 3000 revs, at 3200 revs it will run for about ten minutes and a warning buzz starts up, at 3400 revs the buzz starts immediately. By reducing the revs to idle and placing the gearbox in nuetral the buzz stops after about 15 to 20 seconds. The engine then operates normally up to the above rev range when it goes off again. Ifg I try to continue to run the engine at the 3400 revs it looses power. One thing I have noticed is that the engine does not appear to be using oil. My initial thoughts were the oil is not being injected into the engine, but this seems not to be logical as the engine is clearly operating at lower revs quite well. Water ciculation appears good with a strong flow of water from the exhaust/exit

Any thoughts. Concerned with taking it to a dealer as I recently had a gearbox rebuild and some other things, the dealers response is to replace everything until you get it right. Had some hydraulics issues and they wanted to replace the pump and motor but when I said it was clear the motor was operating Ok the response was thats how we do it. As you will appreciate, I am not confident of a good outcome unless I get a better handle on the problem. ANY thoughts/guidance would be appreciated
 
:eek:I don't know a lot about oil injection,not that modern, but if you think you aren't using oil then you're not and a two stroke needs oil in the fuel. If its a variable injection,ie. it injects less oil at lower RPM's and more as the RPM'S rise,and it's not doing this at the higher revs,you are overheating and damaging your engine.I may be wrong and am open to correction.
But I suggest you don't use it until it's sorted or you'll have a very expensive anchor:D
 
These motors may use a plastic gear to drive the oil pump. ------------I have some that I show to disbelievers ( there are many ) to convince them to mix their own oil.-------------So If you are going to keep " test running " you need to mix at 50:1 ------------The motor is never run on land as a test , without a water supply to the impeller I hope.------In any case a new waterpump impeller is also a wise decision.
 
I have a 90 HP three cylinder two stroke outboard. It runs extremely well up to 3000 revs, at 3200 revs it will run for about ten minutes and a warning buzz starts up, at 3400 revs the buzz starts immediately. By reducing the revs to idle and placing the gearbox in nuetral the buzz stops after about 15 to 20 seconds. The engine then operates normally up to the above rev range when it goes off again. Ifg I try to continue to run the engine at the 3400 revs it looses power. One thing I have noticed is that the engine does not appear to be using oil. My initial thoughts were the oil is not being injected into the engine, but this seems not to be logical as the engine is clearly operating at lower revs quite well. Water ciculation appears good with a strong flow of water from the exhaust/exit

Any thoughts. Concerned with taking it to a dealer as I recently had a gearbox rebuild and some other things, the dealers response is to replace everything until you get it right. Had some hydraulics issues and they wanted to replace the pump and motor but when I said it was clear the motor was operating Ok the response was thats how we do it. As you will appreciate, I am not confident of a good outcome unless I get a better handle on the problem. ANY thoughts/guidance would be appreciated

Hi

You might check the two stroke tank cap there is n litlle tube inside the cap that if it is not cleaned atleased one a year it will blog the air from getting into the two stroke bottle and it cause a sugsion in the bottle it then prevents the two stroke not to flow to the two stroke pump. My engine cut out twice from over heating due to this problem I took out that tube from the cap on my 90 Hp and is running with out any problems.

Hope this will help you with your problem.
 
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