Johnson 48 SLP intermittently bogs down under load

[xcmhs]

I have a Johnson 48 SLP that will idle and rev up fine when it is not in gear but it will intermittently bog down and act as if it is running on one cylinder when I open it up. In one afternoon it will run fine for 10 minutes and then sputters and bogs down running at what might be half throttle. The carbs have been cleaned the fuel does not have water. It has been to the shop twice for this problem and they can not seem to find out what is wrong. Does anyone have a suggestion as to what needs to be checked?

 

[racerone]

They all run great on a hose , that testing means nothing.-------First thing to do on one of those motors is a compression test.----Then check if you have spark that will jump a gap of 7/16" or better with a gap testing tool.----Then you can also run with a timing light hooked up to see if there are spark issues when fault occurs.-----Try running the motor without the cover on as well.--Then again it might be as simple as a leaky o-ring in you hose connecter.----Try running with another tank and hose as well.

 

[Hammy]

I was having the same problem until mine quit completely. Mine I believe is varnish in the carb breaking loose. Right now it is not running. Need to remove carb and soak it in carb cleaner.

Hammy

 

[xcmhs]

Racerone, It was a faulty bulb. I replaced it and it runs fine now. Thanks for your help.

 

[dtoole]

hammy, it is not recommended to soak a marine carb in cleaner. they have a protective coating that will be destroyed . they are cleaned by an ultrasonic cleaner