76 Johnson 25HP 25EL76E WOT Power Problem

[lmifl]

This is a follow on to original post.
Motor ran great 3 times out. Then lost of power to 1/5 speed at WOT.

Cleaned/Rebuilt carb, replaced all fuel lines and bulb. cleaned tank etc. As suggested.

No improvement at all. Finally did compression test. Electric start
wot,nuetral,both plugs removed, 4 cranks 2 to 3 seconds each
Results: 80PSI cycl1 80psi cyl2.

After warm up same as above: 85psi cyl1 82 psi cyl2.

I noticed yesterday that on the upper portion on starter side of motor
that I saw bubbles of gas where the rear of the manifold meets the crank case, when running. Gasket plate to crankcase.
Is this the source of my loss of power and low compression. Shouldn't I be around 100 on each with 10/15%.

Let me know as this has gone on 3 weeks and haven't fished yet.

 

[scrampbell]

Re: 76 Johnson 25HP 25EL76E WOT Power Problem

That could very well be the source of your loss of power, but I don't think it is the cause of your low compression.

The way I understand it is that the compression test mainly tests the "compression" part of the piston's stroke... so only the space between the spark plug and the piston head and only the seals that seal up that space. I don't think that the crank case seal would have much influence on the compression test.

I may be wrong, but I'm confident that someone will correct me if so.

 

[lmifl]

Re: 76 Johnson 25HP 25EL76E WOT Power Problem

Scrampbell


Thanks. Thats the second confirmation on that.

 

[lmifl]

Re: 76 Johnson 25HP 25EL76E WOT Power Problem

Well I hope this is it for awhile.

After all the above suggestions for WOT problem, I think I have it.
Rebulit carb,new fuel lines cleaned carb etc.

Noticed that fuel line connector was not snug against tank connector.

Put the original fuel line back on a put a nylon tie on it to pull it snug to
the out flow connector on tank.

Results WOT BOOH (BAT OUT OF HELL ON WATER)

Thanks for all your suggestions and advice.