86 johnson 25hp compression lock??

[merc350]

hi again. i have an 86 johnson 25 hp. done 15 hrs work in its whole life.
went out today. ran great, for about 30 minutes. stopped, fished, then went to restart, and motor wouldnt start and run properly, and i was getting a major compression lock, sometimes when i pulled the starter.
and wouldnt stay running.
had to get towed back in by the coast guard. bugger.
sometimes it will run, but i seem to be getting the compression lock sometimes when i try to pull start it.
could it be firing too early somehow? it seems to run ok, then gives a big cough then stops. i have checked the cylinders, no sign of water in them. electrical problem? i am ready to drop this motor in the ocean as an artificial reef. would the cdi unit play up and cause it to spark early sporaticly?
not game enough to take it out any more. any ideas ? thanks.
ps.. now it wont start at all. :-(

 

[tx1961whaler]

Re: 86 johnson 25hp compression lock??

Just what is "compression lock" ??
I'm thinking that the motor may have a sheared flywheel key

 

[olgreenboat]

Re: 86 johnson 25hp compression lock??

I would guess it is eather a coil or CDI problem..

 

[merc350]

Re: 86 johnson 25hp compression lock??

Just what is "compression lock" ??
I'm thinking that the motor may have a sheared flywheel key

compression lock is when i pull the starter cord, and the motor starts to turn over, then stops suddenly in a "lock" and nearly rips your fingers off.

 

[tx1961whaler]

Re: 86 johnson 25hp compression lock??

"seems to run ok, then gives a big cough then stops."
"compression lock is when i pull the starter cord, and the motor starts to turn over, then stops suddenly in a "lock" and nearly rips your fingers off."

OK. I'm leaning strongly toward a sheared flywheel key. That totally hoses up the timing. Has the flywheel been taken off recently?

 

[merc350]

Re: 86 johnson 25hp compression lock??

no i havent had the flywheel off. its never been off in its whole life.
i think im leaning toward cdi problems, cause i have petrol getting to the plugs, and everything else, but now i have no spark at all. do cdi units play up and cause eratic spark? its there any way to test the cdi unit, so i dont repalce it, oly to find out its the stator unit? artificial reef is looking good....

 

[tx1961whaler]

Re: 86 johnson 25hp compression lock??

Yes, there is a way to test the ignition.
You didn't mention earlier that you had no spark......you checked it with a timing light or spark tester?
Ignition testing directions here:
http://www.boatpartstore.com/page32.asp

 

[merc350]

Re: 86 johnson 25hp compression lock??

i only just metioned it, because it was still working up till yesterday, then last night when we tried to get it running again, it just wouldnt go. then we discovered that there was no spark anymore.

 

[merc350]

Re: 86 johnson 25hp compression lock??

i have done some investigation and i realise now that the engine is firing, i have spark, but its not firing where it should be. the flywheel has never been off, and i see no signs of it being moved.
it still fires at the wrong time, and stops the pistons dead when it does fire in the middle of a pull start, and almost breaks my hand. GRRR
this is ver frustrating. why would it do this for???

 

[1946Zephyr]

Re: 86 johnson 25hp compression lock??

Remove the flywheel and make sure the key hasn't been sheared off.

 

[merc350]

Re: 86 johnson 25hp compression lock??

ok i removed the flywheel today.
the keylock is fine. not sheared.
now im back to square one. any other ideas?