1st boat motor problems help!!!!!

[1986bassbuggy$@]

I have a 115hp mercury 2 stroke inline 6, that ran great ONCE, and on my family's second time out on the boat it ran great idled a while waiting to pick up my wife and daughter from the ramp after i got them drove out of the no wake zone and gunned it drove for about 5 mins and lost almost all power from the motor, instantly turning around in fear of being strand in the middle of the lake just about to the no wake zone it made a noise that sounded like popcorn popping now at home i changed the octane of the gas to 93 still same noise and it makes a winding noise when the motor is shut off in neutral
PLEASE HELP

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

I don't know if my motor is screwed internally or is it just a fuel or spark issue????

 

[JB]

Re: 1st boat motor problems help!!!!!

You need to troubleshoot it, 86bb.

Is the flywheel key sheared?
Is the compression good and even within 10%?
Does it make good spark on all 6?

Let us know.

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

great blue spark and starts on a dime with 93 octane fuel, it sounds like popcorn popping theres no sequence of the noise just like a random pop, I just bought the boat and this is only the second time ive taken it out the first time was great 9 hours of fishing and playing on the lake now im worried the motor blew, if it helps it makes a grinding noise when shut down even in neutral like gears, maybe the dog sheared???

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

this is my first boat so it really bums me, just enough to let my wife and daughter fall in love with it.
although i dont know boats to well i know motors pretty decent

 

[JB]

Re: 1st boat motor problems help!!!!!

You should not need 93.

Answer my questions, please.

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

any ideas it goes into foward and reverse fine, But it has a ton of vibration when running i fill it in my feet! is there chance there could have been something come loose on the drive shaft ?

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

it has good spark

Not done a compression test

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

how could i tell if the fly wheel key has been sheared??

 

[1986bassbuggy$@]

How can i tell if my flywheel key has been sheared???

How can i tell if my flywheel key has been sheared???

having difficulty starting my 115 hp 2 stroke mercury inline 6 and someone suggested the flywheel key maybe sheared?? is there a way to tell if it has been sheared with out pulling the flywheel?

 

[gejandsons]

Re: How can i tell if my flywheel key has been sheared???

Re: How can i tell if my flywheel key has been sheared???

having difficulty starting my 115 hp 2 stroke mercury inline 6 and someone suggested the flywheel key maybe sheared?? is there a way to tell if it has been sheared with out pulling the flywheel?

Removal of the nut & washer may reveal the two key ways, allowing you to determine if the alignment is proper .

 

[sutor623]

Re: How can i tell if my flywheel key has been sheared???

Re: How can i tell if my flywheel key has been sheared???

Removal of the nut & washer may reveal the two key ways, allowing you to determine if the alignment is proper .

Yes but you are having trouble starting, but why would the first place suggested to check be the flywheel woodruffkey? It could be many other issues, why start there?

 

[MH Hawker]

Re: How can i tell if my flywheel key has been sheared???

Re: How can i tell if my flywheel key has been sheared???

I would think if its running ok once its started it wouldnt be the key

 

[smokeonthewater]

Re: How can i tell if my flywheel key has been sheared???

Re: How can i tell if my flywheel key has been sheared???

YES it's easy..... check the timing with a timing light.... If it is right then key is not the problem.... If it is wrong, remove the top spark plug, feel the top of the piston with a clean probe.... screwdriver worx..... rotate the flywheel till the piston is at the top of its stroke.... find the center of the range where it doesn't seem to move.... look at the timing mark, If the key is good then it should be very close to tdc.

If first test is bad and second is good then do the link'n'synch

 

[rickryder]

Re: How can i tell if my flywheel key has been sheared???

Re: How can i tell if my flywheel key has been sheared???

Yes but you are having trouble starting, but why would the first place suggested to check be the flywheel woodruffkey? It could be many other issues, why start there?

I agree ! Start with the basics.....

@gejandsons Plus just don't say remove nut and washer...... It needs to be retorqued to the proper ft lbs or he will shear a key.....

 

[JB]

Re: 1st boat motor problems help!!!!!

Based on what little we know you might have some mechanical failure and be running on only part of your cylinders. You might also have the timing way out of tune (a sheared flywheel key would do that) or blown gasket(s).

Do a compression test. That will eliminate blown gaskets and mechanical failure of pistons or con rods. You will also have enough information to allow some of our Merc-sperts to chime in and guide you through ignition system and carb system troubleshooting.

 

[1986bassbuggy$@]

Re: 1st boat motor problems help!!!!!

what should the average pressure be on each cylinder or atleast a bare min. i can use as a see the diffrence on?

 

[sutor623]

Re: 1st boat motor problems help!!!!!

what should the average pressure be on each cylinder or atleast a bare min. i can use as a see the diffrence on?

Compression should be within 10% of each other. You need a compression tester. Post up the numbers, and if you really do want ANY help here, best thing you could do is answer JB's questions one at a time. Thrust me most of us are novice compared to him. Only way to get answers on here is to actually do what the boys are asking. We have all been there and done that so you must start with the basics. Youd be surprised how simple some of these problems are to fix.

 

[JB]

Re: 1st boat motor problems help!!!!!

The psi can vary too much from multiple causes to set a standard psi. Go to the Engine FAQs forum and do the test as described. For now your purpose is to prove that all cylinders compress a number that fits into a 10-15% span. There is no possibility that all 6 have failed by the same amount at the same time. If you get them all above about 70psi, tell us what you got and how different your test was from the one describe there.

 

[Gomer50]

Re: 1st boat motor problems help!!!!!

I hope you are mixing your fuel with 2 stroke oil 50:1.I just kinda browsed thru here and noticed you thought you might switch to a different octane but no mention of oil.They don't run very long on plain gas