2005 90HP 2 stroke carbs bogs down on after warmup

[Bronx68]

I have a 2005 Johnson outboard with carbs. Engine runs great at higher rpms. I am have trouble running at trolling speeds after the engine warms up. What is a good troubleshooting procedure? Engine will stall at idle after warm up but still runs great at higher rpms.

 

[willy007]

Re: 2005 90HP 2 stroke carbs bogs down on after warmup

Always a good idea to check the compression & spark when the engine bogs. Additionally, check and make sure that all of your fuel lines are in good shape and connected properly (no cracks or leaks). With the age of your motor i'd doubt that the fuel lines are bad but you may have a loose connection somewhere. Have you taken apart &/or cleaned the carbs at all? Your low speed orifice may be getting dirty or clogged in one of the carbs.

 

[Bronx68]

Re: 2005 90HP 2 stroke carbs bogs down on after warmup

Always a good idea to check the compression & spark when the engine bogs. Additionally, check and make sure that all of your fuel lines are in good shape and connected properly (no cracks or leaks). With the age of your motor i'd doubt that the fuel lines are bad but you may have a loose connection somewhere. Have you taken apart &/or cleaned the carbs at all? Your low speed orifice may be getting dirty or clogged in one of the carbs.

Willy007,
Why would it idle fine before warm up and run perfect at high RPMs both cold and after warm up? Yes I checked hoses and connections and they seem fine. I'm not sure how to take carbs apart so used carb spray and ran high concentration of SeaFoam through them. Is there any way to troubleshoot a problem like this is the approach to just keep trying things until finally something works?

 

[willy007]

Re: 2005 90HP 2 stroke carbs bogs down on after warmup

There is a laundry list of things that could cause the bogging but it's always best to check the easiest and most obvious first. If you're confident that the fuel is getting to the cylinders fine than your problem is most likely an electrical issue. Damaged electrical components tend to work fine when cold but fail after they are brought up to operating temperature. An electrical issue would make sense given that the problem doesn't show up until the engine is warm. After the engine is warm check for a good spark on all cylinders while at idle. It is possible that an electrical component is beginning to fail and the high temps at idle are beginning to make it show (A motor at idle can run several degrees warmer than at WOT). If you have a timing light than you could also check the spark timing at idle as well. I wanted you to check the fuel issues first because they are typically a lot easier to diagnose and fix.