115hp Merc. power loss

[glasstream]

Anybody know why a motor would suddenly lose power?? I was out Sunday, had been running full throttle for about 5min. when the motor started getting louder and started loosing power then just shut down (all happened over a 15-20sec period). After trying for about 2min to restart it, it started back up. Ran with only about 3/4 power and the motor still sounded 'off' but not as loud as when it shut down.
Does anybody know what it could possibly be?
Just need a little help.
Thanks!

 

[wrechin2]

Is this a 4 or 6 Cylinder 115???

I have seen bolt come out of the exhaust cover causing it to get louder. Sometimes when this happens, it can lean out a cylinder and cause damage due to a "NEW" source of oxygen.

For the 2 minutes you tried starting it, what was it doing??

 

[glasstream]

It's a 6 cylinder.
For the 2min it was just cranking like normal but wouldn't turn over. I wasn't constantly cranking it for the whole 2min. If i'm not mistaken, it was on the third try when it finally started. It sputterd for a moment, almost like a cold start, then smoothed out a little.

 

[glasstream]

emoScratch

 

[wrechin2]

It could be several things. Could be from trash in the tank restricting the fuel to a stator getting hot and shutting down. The only thing that that doesn't puzzles me is the added noise. Sometimes when they run out of fuel they will make a different noise and of course you know all noises have their own frequency. So it may just have been a frequency you could hear better and it seemed louder. But it may also be a missing bolt. Seen it on a few engines.

I am suppose to go to the lake the weekend and test a boat for the same issue but without the noise. What I find on it may be totally different from your issue. The only problem is getting it to act up to test. I looked at the other one here and it ran fine, so off to the lake we go. It only happened the one time right?

 

[Fisherman550]

Having similar problem on my 2 stroke 70 hp Johnson-starts great when cold, runs fine for short time, then loses power. When I idle down it dies. It will start back on the first try, but can't keep it running then. This comes & goes. Changed fuel filter, plugs, emptied & cleaned gas tank, nothing helps. Waiting now for my turn to get into repair shop. Seems like lots of people are having troubles right now, at least the repair shop is getting good business.

 

[glasstream]

wrechin2 - 4/16/2010 5:47 PM

It could be several things. Could be from trash in the tank restricting the fuel to a stator getting hot and shutting down. The only thing that that doesn't puzzles me is the added noise. Sometimes when they run out of fuel they will make a different noise and of course you know all noises have their own frequency. So it may just have been a frequency you could hear better and it seemed louder. But it may also be a missing bolt. Seen it on a few engines.

I am suppose to go to the lake the weekend and test a boat for the same issue but without the noise. What I find on it may be totally different from your issue. The only problem is getting it to act up to test. I looked at the other one here and it ran fine, so off to the lake we go. It only happened the one time right?

Yea, it did just happen the one time. Hey Wrechin, are you available to check the motor out for me, or can you refer me to a good mechanic?. Otherwise, i'm taking it to Precision Marine tomorrow.
Thanks for all your help emoThumbsup

 

[wrechin2]

I am running ragged as it is. I have 4 engines to build and about to leave to go look at 2 possible 3 boats this afternoon. Let us know what you find out! emoToast It may be impossible to figure it out unless it can be repeated. That is why I asked how many times it happened.

 

[glasstream]

Found the problem. #3 piston is shot!! emoBadLanguage Guy @ Precision Marine said that he doesn't think it's the lack of water that caused the problem. Possibly timming.
emoScratch
Looks like I'm off the water for the season emoBang
If anyone knows where a 115hp is for a good price, let me know.

 

[wrechin2]

Those engines are pretty cheap to rebuid if you are mechanically inclined. Pretty simple also. The mercury switchboxes are famous for killling engines. I replace both boxes when I rebuild any that use the 7778 boxes. This is assuming you don't have a pre-79 with a distributor. I built a HP engine for myself and used 2 used swithboxes that I had. I then indexed the engine and found that on box was bad and was cross firing all 3 cylinders on the port bank. If I had ran the engine, it would have damaged it. That is the reason I replace them. Never know when one will go bad and kill a engine and I am standing behind my engine for a year.

If you need help or a manual on how to build it let me know. I have one downloaded to a host site you can download. I can also tell you how to build without the high dollar ring compressors. My method cost ya less than $10. Fee free also to call me if you need any information. emoToast Sorry for your luck!

 

[Guest]

I say do ti yourself!!! with a little expert advice thrown in. Its very rewarding. I had to do mine a couple yaers back and I'm very satisfied and the boat runs great, and you think wow I did that and saved so much money.

 

[glasstream]

wrechin2 - 4/21/2010 3:19 PM
If you need help or a manual on how to build it let me know. I have one downloaded to a host site you can download. I can also tell you how to build without the high dollar ring compressors. My method cost ya less than $10. Fee free also to call me if you need any information. emoToast Sorry for your luck!

I'm going to try and build it myself. Could you maybe email me the info on the manual. And I'll be calling you for some advise on your cheaper method. emoSmile My email is [[email protected]].
I can't thank you enough for your help. Oh Yea..it does have a distributor.

 

[wrechin2]

I just threw one of those away!! It is at a buddies recyling shop and I am sure you can get it from him. It was a distributor engine as well.

http://www.chattanoogafishingforum.com/forums/thread-view.asp?tid=42797&posts=6&start=1

I can PM you the link for the manual. READ the instructions on how to use it. I spent a lot of time on the manual to make it "ACTIVE" so it is easier to use. ALL that I ask is if you find a mistake, let me know so I can correct it.

 

[wrechin2]

I talked to him and he said you could get it off the pile!! I get a few minutes and I will go pick it up so it is here. I will have to wait until tomorrow though when he is open.
emoToast

 

[glasstream]

Thanks, James! Give me a holler and I'll come pick it up. It was good talking to you and thanks for the manual, I owe you one emoToast

 

[wrechin2]

No problem man!!!!

 

[2jigs]

James is the MAN!!! emoThumbsup

 

[wrechin2]

2jigs - 4/27/2010 10:56 PM James is the MAN!!! emoThumbsup

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emoThanks emoThanks Did you learn anything over here today Steve???
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[2jigs]

wrechin2 - 4/27/2010 11:04 PM

2jigs - 4/27/2010 10:56 PM James is the MAN!!! emoThumbsup

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emoThanks emoThanks Did you learn anything over here today Steve??? </p>

Yep, I ain't smart enough to be a mechanic! So I'll stick to driving a truck& catching the bass. Andpay you to work on the boat when it won't go! emoLaugh

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[wrechin2]

LOL!!! OK!!! emoToast