55RL76E running on one cilinder

[Malelom]

I bought a boat with a 55hp Johnson engine (55RL76E) and i think it is only running on one cilinder.

I had the boat in the water three times now, the first time no real power, the second time suddenly after 1 hrs of running time the boat suddenly went real fast and the engine sounded a lot smoother, so my first thought was that one cilinder suddenly came in.
Third time the boat was slow again and after that run i checked the sparkplugs.
One sparkplug was a little greyish but not real white and the other plug was brown with a little black like rich fuel. Both plugs where sparking when i tested.

Today i run the boat again for half an hour and after that both sparkplugs are the same greyish colour but the boat was still slow. Both plugs sparked when i tested them.

Does anyone has some advice on where to look as it seems that ignition is not really failing.

My guts tell me that if it is a fuel problem the cilinder wont fail completely and suddenly come in and after that fail completely again but everytime i check the ignition it seems to work fine.

[boats.net]

It is possible that the carburetor is not working on the dead cylinder. But since you have been running with a possible fuel issue. I recommend starting with a compression test. If compression test is good, take silicone spray and shoot through each carburetor (while running) If it picks up rpms, that is the dead cylinder.

[Malelom]

Thanks for the advice, i will do a compression test today and i don't have silicone spray but i guess some starting fluid will work just as fine.

[Malelom]

Ok i have putted a barrel with water onder the engine so i don't have to put it in the water every time.

I tested compression and this was 12 bars/175 psi (top cilinder) and 11 bar/160 psi (bottom cilinder).

After this i sprayed some starter fluid in the carbs and i can let the engine die by spraying in either hole.
I also took some temp. measurements and both cilinders seem to warm up equally so i guess it is actually running on both cilinders.

I can pump up the handfuelpumpthingie untill it is stiff but after a couple minutes running it is squezable again, i checked the little round metal screen filter on top of the fuel pump but no debree in there, tank is also completely clean and filled with brand new fuel.

I made some video's that i will try to upload in this post.

[boats.net]

Based on the supplied information everything looks to check out. The #2 cylinder is a little out of specs, but not wildly. Check your timing advance linkages and make sure they are moving as you accelerate. There should be no play and should advance freely with the throttle.

[Malelom]

Movie 1:

http://img24.imageshack.us/img24/121...ohmfgxigal.mp4

Movie 2:

http://img440.imageshack.us/img440/6...eftrkwsayv.mp4
Movie 3:

http://img24.imageshack.us/img24/121...ohmfgxigal.mp4

[Malelom]

Based on the supplied information everything looks to check out. The #2 cylinder is a little out of specs, but not wildly. Check your timing advance linkages and make sure they are moving as you accelerate. There should be no play and should advance freely with the throttle.

Today i checked the timing and it was a little off, idle was 3 degrees before so i guess ok and fully advanced was 12 degrees before and should be 19 degrees according to manual so that is what i adjusted it to.

I don't really think this adjustment will find me the 50% of horsepower that i am still missing, what do you guys think?

Later this week i will replace all the fuel lines because they are all aged and cracky but i also don't think this will bring me the extra horses...

[Malelom]

I just replaced all the fuel lines from tank to carbs and the squezy thing stays stiff after running now so i guess i fixed another thing.

Hard to tell if the horses came back when running in a barrel so i will throw it in the water when i have time to see if the repairs did some good.

By the way: I notice there are not many replies to my struggling to find the horses, any input whatsoever is still very much appreciated as i am a total newbie when it comes to boat engines.