Outboard lost power after Prop tangled with rope.

[SeaHawk]

I have a '92 Pro50 outboard with a *****ing plate. There is a cloth cable that is attached to the open/close lever which got torn apart by the prop. This was discovered when the motor would not reach a speed greater than 7MPH. I was at WOT all day pushing 30+ MPH until this happened.

After bringing the boat home, I pulled the prop out and everything seems fine. No evidence of rope or anything else behind the prop. I then installed the muffs and flushed the motor. When doing so at idle speed (1100-1200 RPM), the engine RPM would drop 100-200RPM every 3-4 seconds with a sputter and shake of the outboard. The motor does not shut down and the water is existing from all openings as normal.

When I throttle pass 1300 RPM, the sputtering is not as noticeable but still there. I just had a full service tune up with three new carbs rebuilt. The fuel is about 3 weeks old and its 89 octane with a stabilizer. The fuel tank is also new.

Do you think something broke inside the lower unit? I don't think I spun the prop. But, if I did, would it cause a rough idle?

Any suggestions would be kindly appreciated.

[SeaHawk]

More Bad News

I had the outboard looked at today by a marine mechanic. They think it might need new rings.

The compression reading was 125 PSI for the first and second cylinder. The third cylinder was 110 PSI. They removed and replaced each spark plug as the motor ran. Top and middle cylinder was producing strong spark with some idle change. After removing the bottom spark plug, the motor did not change idle but there was a spark.

The mechanic concluded that the rings are probably bad and needs to be changed. He also said there could be a slight chance that the carburetor reeds are bad but he was doubtful. He said the carbs were very clean and functioning properly.

Having the rope get torn by the prop was not the cause of the malfunction. I think it was just waiting to happen.

Any suggestions or thoughts would be helpful? <@((()))<<{

[jb123]

run a strong dose of ring-free or sea foam thru the system to try to clean out some carbon and check comp again.

secondly you COULD have a slight head gasket leak...either way you should pull it and replace it after the fuel treatment just to see the walls, i would just for curiosity.

your plug should tell you if theres any trouble inside.

[SeaHawk]

jb123:

Thanks for the info, I'll pick up some Ring-Free or Sea Foam and give it a try. I probably won't spend the money to have it opened because it cost more to fix the problem then what the outboard is valued at. I'm trying to take the path of least expense.

I just bought the boat and was able to take it out three times and this happens. The motor is a '92 and it WAS in primo shape. My mechanic said the motor looks brand new with only 50 hours of use if that. So I'm disappointed that I got a bummed deal. That's the risk when you buy used. At least the hull is sealed tight.

Thanks again for the advice.

[jb123]

10 % or less is what the comp variation should be...youre right there or above that. but i would STILL pull the head just to see the cylinder walls, your gasket MUST be less that 20 bucks.

[SeaHawk]

jb123


I took your advice and bought a bottle of Sea Foam Motor Treatment and a can of Sea Foam Deep Creep. I will give it a try tomorrow.

Question:
Do you think it is a good idea to remove the spark plug that has the bad ring and spray some Deep Creep to help loosen any gunk? I was planning on pouring 1 pint of Motor Treatment into 6 gallon of fuel to give it an extra boost to loosen the ring.

This stuff sounds promising after researching it on the web in other forums.

Thanks again.

[jb123]

theres a chance it will work, chance it wont....visual is more reassuring.

[SeaHawk]

Attn: jb123

Your are right, it did not cure the problem. The motor does sound better but the problem is still there.

Is it easy to take it apart to get a visual? I have a factory Yamaha service manual for my motor. Its not detailed for a do it yourself. I'm so curious but expecting the worst.