1984 Johnson 115

[brucehick]

Last year I had carbs cleaned because boat was not reaching full speed at WOT. When I pushed Choke in it reached it. This year running much better but still not fully reaching speed. I de-carbed engine poured seafoam in cylinders and let it sit and for one split second it took off. It has since never done it again. I changed spark plugs, pushed choke in while running, squeezed primer bulb and no reaction from engine at all. I have been told by mecahanic that compresion is good but that I might want a lower pitched prop. Its almost like if the throttle could go down another 1/4 inch boat would go. Any ideas would be much appreciated.

Thansk

Bruce

 

[Joe Reeves]

Re: 1984 Johnson 115

We need to know what the compression psi reading is of the four cylinders.

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? The 7/16" gap is important!

I assume that your Fuel Primer Solenoid (choke) is functioning properly or you would have something to say about hard starting when cold. However it is strange that in the past, pushing the key in to engage that solenoid resulted in an increase of rpms... and now it doesn't.

Did your mechanic manually and carefully clean the four brass high speed jets with a piece of single strand steel wire? If not, I'd suggest you do so as carburetor solvent doesn't really clean those jets properly.

Also, remove the craburetor face plate and visually inspect the throttle butterflies to make sure that they are at the full throttle, wide open, horizontal position when at full throttle.

 

[brucehick]

Re: 1984 Johnson 115

We need to know what the compression psi reading is of the four cylinders.

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? The 7/16" gap is important!

I assume that your Fuel Primer Solenoid (choke) is functioning properly or you would have something to say about hard starting when cold. However it is strange that in the past, pushing the key in to engage that solenoid resulted in an increase of rpms... and now it doesn't.

Did your mechanic manually and carefully clean the four brass high speed jets with a piece of single strand steel wire? If not, I'd suggest you do so as carburetor solvent doesn't really clean those jets properly.

Also, remove the craburetor face plate and visually inspect the throttle butterflies to make sure that they are at the full throttle, wide open, horizontal position when at full throttle.

Thanks so much I am going to check those butterflies first if they dont open all the way how would you fix it so they did. Is the face plate hard to get off?

Thanks again

 

[Joe Reeves]

Re: 1984 Johnson 115

Face plate = simply a matter of a few screws.

 

[brucehick]

Re: 1984 Johnson 115

Face plate = simply a matter of a few screws.

Great! I will give it a go next weekend. Also looking into a compresion tester just to be sure its not a bigger issue.

Thanks so much