Mecury 115 4 stroke motor issues

dmctruby

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I have a 2010 Merc 115 on my 2010 model 2250 RCW The last two seasons it ran flawless. This year, last month it began hesitate when throttling up and would not exceed 2500 rpm. I would have to shut down and restart several times and reattempt full throttle before it would run normally. It also randomly had starting issues and some idling problems. All inconsistent. Fine one hour and not working the next. I do have clean fuel filters hi and low pressure, new gas, water separator so I am pretty sure it is not an issue with the gas. These motors do have a tell tale sign there is an issue with the complex fsm (fuel supply module) If you check your air filter on the air intake and it is falling apart (bits will get sucked into your engine). That degrading of the foam is from excessive gas fumes in the vent eating the filter. So I did have that issue. The intakes were cleaned. The dealer is now looking at the rest of the engine. I am convinced one , several or all of the fsm elements are defective. There several elements in that system. One I know is some type of fuel float that hangs up. Other elements that manage the fuel I think could also be bad. The dealer is doing some other checks first but I am watching my prime boating weeks disappear here and was hoping some one else may have found and fixed the problem. At the very least if you have a Merc 4 stroke go check your air filter and make sure it is not degrading and going into your engine. It will fall apart if really bad. Early stage damage will just show the filter to be very tacky or gooey and ready to break down
 
45 views and no comment so far. Huuummmm. No one is running with a Merc 115 4 stroke ?
 
Sorry I have a Yamaha 115. Best of luck though!
 
Running without a problem. Thanks for the info. Keep us posted as to the solution.
 
A friend of mine has the 115 on his toon, it's an 08 model, and yes he had the same issue with the filter breaking down, and he was quite shocked at the price of a new one.

Otherwise, he has had no running issues, but currently has water getting into his lower unit, we'll be looking into that this weekend.
 
I use K&N in my cars . I know they offer some marine options ( don't know if the lifetime warranty is on marine applications ) . I will contact them ,and post their reply .

I had though about one a while back ,never followed up .

I also don't want to void my Mercury warranty , I have to check on that also .
 
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Here is the response from K&N

Hello,

Thank you for your interest in K&N products. We do not make any application specific air filters for outboard engines, however we do offer a wide range of universal filters. You can search for filters by dimension on our website by clicking the link below, or you can also call our customer service at 1.800.858.3333 for assistance.

http://www.knfilters.com/search/universal.aspx

Thank you for writing and have a great day,

Denise O’Neil

K&N Engineering, Inc.

1455 Citrus St. Riverside, CA 92507

1.800.858.3333
 
1st thanks for the responses, I knew this was a great group. It is important to note if your air filter is getting "eaten up" you have a much bigger problem than replacing the air filter. That is a sign you have an issue with one or several of the fsm components.....fuel pressure reg, vac hose, fuel float switch, or one of the pumps. All components live under one cover and are referred to as the fsm. The fsm is then regulated by the PCM. You may not experience a dramatic issue at 1st. It may begin as hard starting, rough idle, stalling, or not getting full rpm from full throttle. It will eventually get worse
 
Update. Was out with the marina Merc tech today and had his diagnostic computer hooked up. The motor did experience fueling issues so he was able to capture that and sent it off to Merc support today for review. Actually was able to capture the rough idle behavior as well as the issues with the motor stumbling trying to get up to speed. Erratic rpm was also captured. So now I await final word from Merc with an expectation parts (presuming fsm components) being shipped next week. Dealer said he would have it running by next weekend Lets hope this is my 3rd lost weekend and two full lost week days of boating ....I can't stand much more down time. Poor kids had expected several tubing outings that we had to cancel due to the motor issues
 
I hope they are able to correct the problems with your engine and have it ready very soon. The season is way too short when everything is good!

GOOD LUCK!!!!
 
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Thanks Dan. It really is no fun to see these nice days slipping away unable to use the boat

I hope they are able to correct the problems with your engine and have it ready very soon. The season is way too short when everything is good!

GOOD LUCK!!!!
 
Not all marina gas is 100% gas. Our marina uses ethanol and the pumps are not labeled.
 
I believe one of the few places in ct you might be able to get ethanol free gas is at an airport. Our marina only uses hi-test but it does have ethanol. I am not ready to blame ethanol as bad as it is for the fueling issues. I think Merc had poor quality components and or design elements of that complicated FSM systems which make it prone to problems

Not all marina gas is 100% gas. Our marina uses ethanol and the pumps are not labeled.
 
I believe one of the few places in ct you might be able to get ethanol free gas is at an airport. Our marina only uses hi-test but it does have ethanol. I am not ready to blame ethanol as bad as it is for the fueling issues. I think Merc had poor quality components and or design elements of that complicated FSM systems which make it prone to problems
At the time of purchase ( 5/31/13 ) I was able to upgrade to 7 year Platinum coverage for just over $400.00 . $25 deductible and no worries for 7 years .It is transferable when I upgrade the boat .

http://www.mercurymarine.com/media/mercury/pdfs/service-and-support/Compare-Gold-and-Platinum.pdf
 
Good new. My awesome marina Brookfield bay got the motor repaired today . It needed a new float switch . I ran if for an hour just now and it seems good. Will give it lots of use this weekend and hopefully confirm it is fixed
 
Excellent !!! Glad it worked out !!!
 
I have two full days of use since the repair and all is well with the motor running. I do have a new rattle from somewhere in the stern. I know the shielding under the boat had some crappy pop rivets let go. I fixed a few of those in the past, hoping that issue is something easy to resolve
 
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