Serious lack of power

[KoenBrink]

Hi guys!

I'm the owner of a 25hp Johnson Seahorse 1977. One problem , it has a huge lack of power, probably it has the power of a 8hp or something like that (going about 6 mph). But sometimes it's feels like I'm flying with my boat (about 20 mph).

So I started to look for the problem. After a few hours of cruising with my boat at about 6 mph I discovered air bubbles coming from the bottom of my extended long shaft. After a closer look I discovered the airflow was coming from the joint between the extension part and the lower unit. Also, when I get the motor out of the water, there's leaking a lot of water out of this joint.

So, does anyone know if the lack of power is due to the leakage in the lower unit, and means this that I'm running this motor without any lubrication inside the lower unit or gear case?

See the pictures.

 

[F_R]

Re: Leaking lower unit

Re: Leaking lower unit

Hi guys!

I'm the owner of a 25hp Johnson Seahorse 1977. One problem , it has a huge lack of power, probably it has the power of a 8hp or something like that (going about 6 mph). But sometimes it's feels like I'm flying with my boat (about 20 mph).

So I started to look for the problem. After a few hours of cruising with my boat at about 6 mph I discovered air bubbles coming from the bottom of my extended long shaft. After a closer look I discovered the airflow was coming from the joint between the extension part and the lower unit.

So, does anyone know if the lack of power is due to the leakage in the lower unit, and means this that I'm running this motor without any lubrication inside the lower unit or gear case?

See the pictures.

There is no gasket in that seam, and they do leak..it is not a problem. Anything that leaks out there was destined to go out the underwater exhaust outlet anyway.

It is almost 99% guaranteed that your motor is running on one cylinder. Start with a new set of spark plugs and a compression check. Once you determine that is not the problem, pull the flywheel and fix the igniton. It is NOT a carburetor problem so don't get trapped going down that road. But it could be a ruptured fuel pump diaphragm. You might want to check that possibility before pulling the flywheel. Simply unbolt the fuel pump from the powerhead (leave the hoses connected) and squeeze the primer bulb. If gas squirts out the hole in the back of the pump, the diaphragm is ruptured.

EDIT: Oops, I just noticed the year, 1977. Your motor has CD ignition, so there are no serviceable parts under the flywheel, only replaceable. Check for spark on the plug wires and if you have a strong spark (7/16") the ignition is ok. Now I'm betting on the spark plugs.. Sorry about leading you down the wrong path.

 

[KoenBrink]

Re: Leaking lower unit

Re: Leaking lower unit

Thanks F_R,

I did test if it was running on one cylinder. I pulled out one of the spark plug cables and the motor just runned further on one cylinder (but of course not as good as on two), I did the same on the other cylinder with exactly the same result.

But the ruptured fuel hose/pump could be the problem, because there's always a little layer of oil inside my motor even very soon after I cleaned it.

I'm going to check it this evening.

Thanks!

 

[KoenBrink]

Re: Leaking lower unit

Re: Leaking lower unit

I checked the spark plugs and also got the carburetor out. Everything looked OK. When I was doing that I discovered that there was a lot of blue oil on the bottom of the housing. The blue color was probably coming from the blue 2 stroke oil in my fuel. There was also a lot of fuel in the air filter/silencer (black box) in front of the carburetor and in the carburetor itself.

I also noticed that the primer bulb is never getting hard.

So I think there's a leakage or something inside the carburetor. :S

Someone any suggestions what to do next??

 

[tashasdaddy]

Re: Leaking lower unit

Re: Leaking lower unit

read ethanol, compression check and carb cleaning, other good stuff here. >>>http://forums.iboats.com/showthread.php?t=299680

 

[coolguy147]

Re: Serious lack of power

i would probably just go ahead and replace the fuel line

now see if pumping the primer bulb while running see if that helps the motor go faster if yes then fuel pump needs rebuilt