1995 Johnson 50hp...will not run at idle

[grumman50]

I recently purchased a 1995 Grumman pontoon boat with a johnson 50 hp outboard engine. The engine looks really clean and has no trouble turning over, but will not start without manually pumping the throttle, and once running will only remain running with throttle pressed. The engine will not idle, but just dies when throttle is released. I have changed spark plugs with no change in results. I have tested for spark with and it passed. Any advise on next step? Can I clean the carbs while still on engine or do I have to take them off?

 

[Lone Duck]

Re: 1995 Johnson 50hp...will not run at idle

What fuel tank are you using? permanent or portable? In any case the first step is to check all fuel lines for air leaks, check bulb, then crank it over , if it does not start check if plugs are wet if not, check for compression if good, then go to fuel pump, if good then go to carbs. I am assuming that you have already checked for spark. If you have a built in tank, check if screen is clogged with junk from tank.

 

[Haffiman]

Re: 1995 Johnson 50hp...will not run at idle

If been sitting for a while, might be time to clean the carbs. Remove, buy a spray can of 'carb and choke cleaner', dismantle and spray through all cannels and jets. Have new gasket kits(2) ready and replace gaskets.
Check that the primer solenoid works properly -spray when key is pushed in, and not leaking when primer bulb is pressed hard. Be sure the nipples in the carbs are open as well.

 

[SparkieBoat]

Re: 1995 Johnson 50hp...will not run at idle

clean your carbs...instructions in the secret files section.