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Engin cutting out at higher RPMs
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| 13sport |
Posted on 08/02/11 - 7:15 AM
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Hello everyone! I am a new Boston Whaler owner and a first time poster. I recently purchased a 1992 13' sport with a 40 hp Yamaha. The price of the boat and overall condition was too good to pass up, apparently classic Whaler's are hard to get your hands on, even in South Florida. I am still pretty new to boating and overall boat mechanics so I figured this boat was perfect for a learning tool, get me my wife and two small kids out in the backwaters, and a chance to have a classic looking boat.
I had a 100 hour service conducted on the boat a few weeks ago and most everythign checked out. New water pump and prop (aparently the old one was seized and needed to be "broken" to be removed to replace some seals), were the only extra maintenance recommended.
The first time out on the boat the engin ran a little rough and would not allow me to increase speed past a "slow speed" to try and get on plane. The engin would simply cut out, no puttering or anything. We used the boat the rest of the day basically ideling around. When washing to boat and engin at home the RPMs can get reved up using easily.
The second time out this past weekend the boat ran much smoother, very little vibration at all, and allowed somewhat of a faster speed however would cut out once again trying to get on plane. Periodically the RPMs would increase by themselves, then go back down. On the way back to the dock I put the throttle down during one of these "episodes" and the engin allowed us to maintain the speed and we got up on plan rather nicely. I am wondering if the boat is just working through some engin "gunk" caused by a few years of sitting. Hpefully that is just the problem. Once again at home while flushing the engin the RPMS would rev nicely when prompted, even when including the propeller in gear. Seems like the extra tork necessary in the water is causing the problem.
Any suggestions?
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| SSI_Whaler |
Posted on 08/02/11 - 7:32 AM
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I have a 1993 13' with a 40hp Yamaha (I'm assuming you have the 2-stroke). I had the same problem and my mechanic disassembled and cleaned my carbs. This completely solved the problem and the motor runs like a top. Can't remember how much I paid, might have been around $100 or so. Good luck!
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| 13sport |
Posted on 08/02/11 - 7:35 AM
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Yes, it is a two stroke. I was thinking the carborator as well, but was a little confused why it would run nicely at low RPM but not a higher RPM. Once again I am not well versed in mechanics, but figured more force through a sticky carborator would be better than less. Hopefully this is just the problem, I was happy to see the boat actually got on plan. It would have been nice to allow it to run open for a while, but ironically we hit an idle speed zone just as we were making our way back to the dock.
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| SSI_Whaler |
Posted on 08/02/11 - 7:41 AM
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I'm not sure of the mechanics either but I too was able to putter back to the ramp after it started. The 2-stroke Yamaha 40 is a great motor for this hull. Mine tops out around 38 mph with just me just in it (using GPS app on Iphone to measure speed). You will really enjoy your boat once it gets the kinks out!
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| Gamalot |
Posted on 08/02/11 - 8:05 AM
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13sport wrote:
Yes, it is a two stroke. I was thinking the carborator as well, but was a little confused why it would run nicely at low RPM but not a higher RPM. Once again I am not well versed in mechanics, but figured more force through a sticky carborator would be better than less. Hopefully this is just the problem, I was happy to see the boat actually got on plan. It would have been nice to allow it to run open for a while, but ironically we hit an idle speed zone just as we were making our way back to the dock.
I often see sediment, dirt and water sitting at the bottom of the carb float bowl. If this is the case with your carbs it is likely when your are at full throttle this junk is being suctioned in to the jets while it may not be clogging things at a lesser RPM. If you are mechanically inclined it is a fairly simple job to remove the carbs and dump the bowl and clean things up in side. You can buy rebuild kits and possibly only need the gaskets.
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| Phil T |
Posted on 08/02/11 - 8:08 AM
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The carburetors (you have more than 1) has tiny passages that can get clogged.
Make sure the fuel is new. Any fuel from the prior owner could be old.
1992 Outrage 17 I
2019 E-TEC 90, Viper 17 2+
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| tedious |
Posted on 08/02/11 - 8:09 AM
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You need to get the carbs cleaned out, and make sure the rest of the fuel system is clean, and then do a "link and sync" on the motor. You do not want to run the motor in its current condition - althought it's unlikely, you could damage or destroy it.
Also, you do not want to be revving the motor up in the driveway on the muffs. At best, it tells you nothing about how it's going to perform on the water. And at worst, if you really rev it up, you can get into a runaway condition where it won't shut off until you pull the fuel line and it uses up the fuel in the carbs - or destroys the motor, whichever comes first. Don't do it.
Tim
Edited by tedious on 08/02/11 - 8:22 AM |
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| 13sport |
Posted on 08/02/11 - 8:20 AM
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Thanks for the information. I did not realize that was a possibility, hence my using this boat as a "learning experience"....already learning a lot.
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| tedious |
Posted on 08/02/11 - 8:24 AM
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Rebuilding the carbs is actually pretty easy, and the link and sync is not hard either if you get the factory service manual. Might be a good way to learn about it, and would definitely save you some $$!
Tim
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| bmw90w |
Posted on 08/02/11 - 11:16 AM
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The reason why is there are low and high speed jets. Rebuilding is easy if you pay attention to parts. If it seems daunting, it is not too expensive to have done professionally.
1984 Montauk |
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| John Fyke |
Posted on 08/02/11 - 2:15 PM
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Clean the carbs and change the fuel filter.
John Fyke
Re-Fit or Reef It
1979 15' Sport with Super Sport conversion and 70hp mercury. |
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| CES |
Posted on 08/02/11 - 2:44 PM
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I have the same engine on my 13'......I had to disassemble the carbs completely, remove all the varnish and all the gunk, then reassemble. It's been running great ever since.
Also I only use Yamalube for the oil to mix with my gas. Additionally, I run Yamahas "Ring Free" in the fuel about twice a year. The first time you use it, you'll have to "shock" it...... you'll be amazed at how well the motor runs after you do those things.
The Yami you have is practically indestructable.
Edited by CES on 08/02/11 - 2:44 PM
Cliff
1966 13' Sport with a 1993 40hp Yamaha 2 Smoker |
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