1963 Johnson 5.5 not going full throttle in forward.

[kleinwy]

I have a 1963 Johnson 5.5 that won't rev all the way up in forward but it will in neutral and reverse. I've heard that it's a fuel problem but the carburetor got cleaned and rebuilt and all the fuel lines are new. Any idea what the problem is?

 

[racerone]

Perhaps it is running on just 1 cylinder.-----So post the actual results of a compression test.-----Does spark jump a gap of at least 1/4" on both leads?----Perhaps the slip clutch in lower unit is binding.

 

[kleinwy]

Perhaps it is running on just 1 cylinder.-----So post the actual results of a compression test.-----Does spark jump a gap of at least 1/4" on both leads?----Perhaps the slip clutch in lower unit is binding.

I did a compression test not too long ago. I don't remember the results but I know it's good compression. And I don't know about the spark plugs but they are brand new so I'm assuming they're fine. But I'm not positive about the clutch. Is there any test I could do for the clutch?

 

[kleinwy]

I did a compression test not too long ago. I don't remember the results but I know it's good compression. And I don't know about the spark plugs but they are brand new so I'm assuming they're fine. But I'm not positive about the clutch. Is there any test I could do for the clutch?

I just took it out on the water and it started to get up to normal rpms when I would turn it fast and put a lot of load on it

 

[kleinwy]

I just took it out on the water and it started to get up to normal rpms when I would turn it fast and put a lot of load on it

I also just ran it out of the water and it got to full rpms in forward when it wasn't pushing the boat. But as soon as I put it back in the water it didn't want to get to full throttle

 

[racerone]

Did you just ruin the water pump by running it dry.----Also was a meaningless test !

 

[kleinwy]

Did you just ruin the water pump by running it dry.----Also was a meaningless test !

No I only ran it for a couple seconds trimmed up then put it back in the water.

 

[Edchris177]

Your test didn’t prove anything. Out of the water, there is no load, it will rev to hell & back, on only one cylinder.
New spark plugs don’t prove good spark. Get an air gap tester, or make something like this. As Racer asked, do both leads jump a 1/4” gap with a hot blue spark?