Question about Yamaha 40N/50N 40 and 50 HP Outboard Motor Service/Shop/Repair

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My Yamaha Outboard 115hp 1994 motor starts but wont keep its revs up for very long. I've had issues with water in the fuel recently and had all old fuel and water flushed out of my tanks and motor. After having it all fixed the motor seem to run up to 40K rpm and as I pull back down to neutral, the motor cuts out. Tried to start it again but no joy as it starts up and revs up to 7-10k rpm then slowly cuts out again. I've replace new bulb primer and fuel lines including filter. Spark plugs have been replaced and are the correct ones. The carby has been taken apart and clean out. I cannot think of any reason why else this could be happening. * This maybe under the incorrect heading as there is no drop down for outboard motors.

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  • 23 Answers

Not enough information, but there are two things I didn't read about you checking. Make sure the fuel quick connection on the engine (and possibly the fuel tank) is locked all the way in first, Then see if your fuel pump is working. Disconnect the fuel line from the carb and, holding it in a gas can, have someone turn on the ignition. If It's an electric pump, it should start running fuel, if mechanical, they'll have to crank it a little to get fuel going. If you get plenty of fuel that way, your float in the carb could have gotten stuck, or something in the line got into it.

Posted on Mar 26, 2017

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6ya6ya
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Posted on Jan 02, 2017

  • 74 Answers

SOURCE: 1995 honda cbr f3 wont start

I would think about investing in a carb re-build kit.

Posted on Dec 22, 2008

Fame_Guru
  • 483 Answers

SOURCE: Yamaha outboard motor manual

You got it :

http://www.yamaha-motor.com/outboard/service/viewmanuals/outboard_manuals.aspx

here !

Posted on Mar 20, 2009

  • 23 Answers

SOURCE: GSXR 750 Slingshot wont rev past 5000rpm, with or without choke

I have seen this before a few things to do too make sure. First take the air filter out and shine a light use your fingers to move the slides up and down I suspect the springs that go on the slide is not seated in center you can tell from the slide going halfway and hanging up. Next, the boots on the slides only go on 1 way there is a notch on the carbs for them. I would guess this would fix you up if not we can get deeper into it with air-fuel mix screw settings.good luck

Posted on Mar 25, 2009

mcgyver468
  • 710 Answers

SOURCE: 40hp 1987 yamaha outboard motor will run for 30-60

Sound like the fuel pump is not keeping up with the engine's demand. Check it out. Good luck. Hope this helps.

Posted on Apr 27, 2009

  • 64 Answers

SOURCE: 94 yamaha 535 virago sounds fine, just wont start

Check to make sure your getting gas by pulling off the hose, if no gas comes out your petcock is clogged. If this is the case blow air up into the hose, and if gas comes out now your tank has to be cleaned out.

Posted on Jun 23, 2009

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here is a good place to start ok Outboard (wiring A Tachometer To An Outboard, Mercury Outboard Float) safe.gif
merc outboard motors mercury outboard ... diagram of mariner outboard motors johnson outboard fuel problems ... johnson outboard motors ebay 1996 115 hp mariner outboard
  • tipsterdatabase.com/mods.php?id=outboard
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40hp 1987 yamaha outboard motor will run for 30-60


Sound like the fuel pump is not keeping up with the engine's demand. Check it out. Good luck. Hope this helps.

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