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Posts: 23
| I have a new 2005 Yamaha 115hp 4-stroke motor that I bought in May,
and I took it out on the river last Sun., and it ran rough, like it was not
getting enough gas, and it seemed like it wanted to die on me. I have
put only 10-12 hrs. since I bought it, and still have the same gas in it
from my trip to Wis. in early June. I have had someone tell me to put a
higher octane gas in it and run it up and down the river for a while, that
these motors are meant to be run good, and not a lot of idling like I have
been doing. Does this sound right? Could the gas with the ring-free in it have
went bad in only a couple of months? Could it be a more severe problem?
I have talked to a couple of Yamaha dealer's, and they just tell me to bring
it in. Does this problem sound familiar to anyone? Any ideas or suggestions
would be greatly appreciated.
Thanks, Greg |
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Posts: 32954
Location: Rhinelander, Wisconsin | There are so many possibilities that it's a wild stab to guess at a rough running 4 stroke. I would look at the fuel line and bulb and the spark plugs first, if nothing there and the problem persists, tkke her in for a mechanic to look her over. |
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Posts: 23
| Thanks Mr. Worrall, I did pull the plugs, took the filter cup off, smelled the gas,
made sure the float was still on the bottom of the cup(no water), poked and
prodded everything else and found nothing that looked out of place. I filled up
with 91 octane and ran it on the river for a while. It did run rough for the first
10 minutes or so, and after that it smoothed out to normal. Maybe these motors
do need to be opened up regularly. The only muskie waters around me though
are either no wake or electric, so I will have to make the effort. Thanks again.
Greg |
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Posts: 561
Location: Monee, Illinois | I have a Johnson 4 stroke and thought it ran ruff, I just got done with my 20 hours on the motor and took it in for the 20 hour check up. If you havent done this yet make sure you get your oil changed and what ever else your 20 hour check up intails. They also told me 20 hours or 3 months what ever comes first. They make adjustments to the motor during that period (the computer in the motor tells them the adjustments) so I would just take it in. Tell them your problem and it will be taken care of. I love the 4 stroke, mine is a 140HP and sometimes I think its running false but its just runs so soft.
pga |
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Posts: 457
Location: Minneconia | Hey IowaG,
Where in IA are you? I live in DSM and also have a 115 Yammy four stroke that I'm just now breaking in. From what I have heard you should only run 87 octane in these motors, its what they are designed to run on. Also, did you run the motor up and down during break in(First ten hours)? Have you changed the oil yet? I'd take her out to the nearest no restriction lake and run it at different rpm levels for a couple of hours, you should also load the rings on it during break in by gassing it hard a few times to maximize the motor's potential. Hope this helps, you also might want to look into a water separating fuel filter.
Roger B. |
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Posts: 23
| Hi Dirt Esox,
I live over here in Muscatine. I tried doing the breaking-in up in Wis. on vacation in early June. I ran it at
2000 rpm's the first hour, and 3000 rpm's the 2nd hour, but it was not all continuous. Since then, I have
not had the opportunity to run it much, with the river flooded most of June, and waiting to get a new prop
(rock bar in Wis.). The owner's manual says a min. of 86 octane, but the dealer I bought the boat from did
say the same about it being made for 87 octane. I ran it yesterday at 5000 rpm's for a half hour, and then
back to the dock at 4000 rpm's, and it went back to running normal after 10-15 minutes @ 5000 rpm's.
With what you and Pgaschulz have said, I am going to get the 20hr. service done even though I have not
put 20 hrs. on it yet. Thanks for all the info.
Greg |
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| Ive got a 2001 Yamaha 80 4 stroke.The thing ran like POOP for the first year.Went back to the dealer many times only to hear that it was my fault somehow.IE Bad gas,too much oil,to much alcohol in the gass,Timming was 10 teeth off.Untill one day the service tech thought he was going to be cute and call Yamaha on the speacker phone so we could here that it was MY fault.When much to his disgust the tech at Yamaha said that they had a problem with the floats sticking open after a day on the water.So after a YEAR of BS it got fixxed and has been a purring pussy ever since.Have them check the floats in the carbs!!Good luck Kyle www.smokertackle.com |
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| I have a 40hp Merc 4 stroke and I have found that after a few trips out when the motor idles most of the time it starts to run rough. I found that a fresh tank of gas with some seafoam in it, then run in almost wide open for about a half an hour and it will run great again for the next few trips out. I was told by a tech that these 4 stroke motors have very small jets and they are know to gum up a bit when run at slow speeds with less than fresh gas.
I hope this helps, good luck. |
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Posts: 166
Location: Gurnee, Illinois | The 115 is fuel injected so no floats or jets to check or clean. You may have filled up with a bad tank of gas to begin with. Use 87 octane, and go fill up at an Amoco, Shell, Mobile etc. and try again. I have a 03 115 and she runs good and starts real easy but you also need to let the engine come up to temp before it will run real smooth. I have had mine burp and even stall at low RPM's when the engine is cold. Try the new gas thing, and if that doesn't work, take it into the dealer. There is a onboard diagnostic system on your engine, and when the dealer plugs into a laptop, they have all the running perameters such as temps, max rpms, run time, etc.
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| Guy's,
I just bought a 2002 Mr Pike 17 (LUND) with a 115 Yamaha 4 stroke 2002. What size prop should I be looking at in a stainless steel prop. It has a aluminum prop and I hate the way it is dinged up allready. It looks worse than my stainless prop I ran for 10 years on my Johnson 150. I am thinking abought trading my stainless prop from the Johnson for one that will fit on the Yamaha.
Thanks for the Help
Steve |
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| Gas now a days can go bad on you in only one month. That is a fact. If you are not going to be running your fuel out very often you will have to add a gas preservative to it. I use sea foam. It also cleans out any build up you might have. Its good stuff. I use it on everything. |
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