15 rope start failure

[sugarfish]

Im looking for a bit of advice on a 15 hp, Johnson 1995 tiller arm rope start on a little dingy I have in the Bahamas.. It has been really reliable for me for a couple years now, with just some carb problems that is pretty standard with the dodgy fuel we can get.. Last week I was running it as a rescue boat.. I left the dock and had to run a couple miles to the location? Half way there with the engine running great the engine suddenly pretty much dies.. I eventually get it to run in neutral on one cylinder, but really rough.. Looking into it further it will not run on the bottom Cylinder, this is with new plugs. Further more both plugs are firing strong. I noticed some black fuel hose residue in the carb bowl so replaced the hose and installed an inline fuel filter.. I checked the fuel pump screen, and the diaphragm.. I cleaned the carb, really cleaned the carb that is.. and it still will not run on the bottom cylinder.. This is with putting some gas in the spark plug hole and cranking.. Im pretty sure I have ruled out fuel.. I have strong spark, or so it seems anyway on both plugs? So where do I go from here?
- Can I somehow throw off the timing while underway with out hitting anything?
- Does this sound like the mysterious reed valve failure ?
I didn't have a flywheel puller or compression check gauge to diagnose further. Im in the US for the holidays and want to bring back parts and tools and get to the bottom of this. Any help would be much appreciated..

 

[boobie]

Re: 15 rope start failure

What you need is a compression tester and an open air gap spark tester set at 7/16" open air gap. Do the compression test first and if it passes look for something else. Then check your spark.

 

[dkonrai]

Re: 15 rope start failure

head gasket? i have seen a couple that had blown gaskets motor would run but not idle no real power. couldnt tell without a compression gauge tho both motors had low compression. when i pulled the head both had small failures that caused hard starting and off idle issues.

what do the spark plugs look like? post a picture of the plugs. if both are the same color and smell of gas then the carb is ok.
could be a bad coil too? do you get a nice blue spark? white is ok, blue/white is better.

jmho.

 

[sugarfish]

Re: 15 rope start failure

Thanks for the reply?...I will be certainly bringing both those tools back with me. I really wish I had that information to post, and I understand how amateur it is to even think I can diagnose with out a compression check.. Don't laugh, but all I can add is that with no plugs installed the compression is about the same on both cylinders? ( measured by blowing my thumb off the hole)
It is really hard to get parts down there, and I was hoping to bring a couple things back if I had a clue to go on.. Like perhaps a flywheel key .. Is that even possible that sheered? or a set of reed valves.. I know I should have some patience and do it right.. At least I'm bringing a manual back,, so perhaps there is hope.. Thanks again..

- Just saw this about the head gasket.. It definitely is not running on bottom cylinder at all, and definitely not idling.. The plugs are new, and although I didn't have a Carb rebuild kit I cleaned all the jets, even ran some finger drill bits through them.. and am really pretty confident that my fuel system is strong.. Something catastopic happened all at once, it was running and idling great previously. I cant say anymore on the spark? I really wanted to check it in the dark and see what the color was.. all I can say is that both plugs are sparking about the same.. but its running on the top cylinder only.

 

[boobie]

Re: 15 rope start failure

Don't forget to take a head gasket with you.

 

[sugarfish]

Re: 15 rope start failure

I have decided to shoot this project with the money gun.. The parts I don't use will be great for spares.
- ignition coil, power pack, head gasket, carb kit, fuel pump kit, leaf valve assembly, flywheel key, and all necessary gaskets.
- Engine manual, Flywheel puller, open air gap spark tester. compression tester.

Thanks for the advice, and support.. I will be back on Island in a couple weeks and hopefully get to the bottom of this..

 

[boobie]

Re: 15 rope start failure

Make sure you update us as to what you find.

 

[sugarfish]

Re: 15 rope start failure

I wasn't able to get the parts I ordered in time before I caught the plane.. Which is perhaps a good thing.. I just did a compression check, and I'm getting 118 on the top cylinder, and only like 45 on the bottom cylinder.. Where should I go from here? Could it be as easy as a head gasket or am I looking at a rebuild?

 

[racerone]

Re: 15 rope start failure

Remove cylinder head for an inspection first !

 

[F_R]

Re: 15 rope start failure

Agreed, pull the head. If the gasket isn't blown, the piston probably is. Aren't you glad you didn't buy all those parts?

 

[sugarfish]

Re: 15 rope start failure

Cylinder head removed.. .. There is some damage to the bottom cylinder, Piston top.. There are knicks and metal flakes in the combustion chamber side.., ... Something was banging around in there.. The cylinder walls don't seem scored though.. There is no obvious damage to the head gasket.. must be a ring failure I imagine? Im going to try and attach a pic…
Ya …. F_R im pretty bad at jumping the gun when it comes to repairs.
So what now?…

 

[racerone]

Re: 15 rope start failure

Rebuilt one of those motors where a piece broke off the piston skirt.----There is not enuff room in the crankcase for loose pieces.--------Time for a complete teardown.

 

[sugarfish]

Re: 15 rope start failure

ya.. I was afraid of that… im not sure if thats worth it with where Im at here in the Islands…. Whats your thoughts?
I pay 50% duty on outboard engines, so replacing gets pretty expensive.. Could I have caused damage to the block when I was making it run on the one good cylinder? I guess I need to take a look and see what failed to get an Idea of rebuild costs… Do you have any insights on a ball park figure what a rebuild could run? I travel alot for work and am supposed to do a stint in Asia here soon.. I wouldn't want to go much further on this project until I could devote some time too it.. Nothing worse than tearing something apart and than waiting 6 months..
Thanks though for the advice.. learned a bit along the way.. im going to spend some time on one of my boats that works… Happy New Year..