studddering at wot

[lastout]

gentleman, my 1971 60hp johnson has a slight, pulse like studder in the upper throttle range. the carbs are clean, fuel system is good, and all the other items i can think to check are checked. i am running a 17 pitch prop on the engine on a 16 foot fiberglass center console tri-hull if this matters. i would appreciate any thoughts on what to check that i may have missed. thanks

 

[Solittle]

Re: studddering at wot

Do you have an inline water seperator. Sometime a bit of water in the fuel will do that.

 

[lastout]

Re: studddering at wot

no such luck, no inline water seperator. i'm at a loss right now.

 

[ob]

Re: studddering at wot

What is your engines wot rpm capability?Not withstanding another issue that may be present in your engines performance ,I'm thinking that a 17" prop is a bit steep for a 60 pushing a 16ft. tri-hull.What happens if you try pumping the primer bulb when engine is stuttering?

 

[lastout]

Re: studddering at wot

not quite certain about the rpm's, i don't have a tach. i did however try a 15 pitch prop on this boat and it ran like poop. would barely plane and certainly didn't reach a proper rpm level. the primer bulb is stiff and fuel is flowing fine. the carbs were cleaned and floats adjusted recently. it seems to me that the boat wants to reach higher rpm's and could probably stand to, for some reason it just ain't happening. the timimng is advancing to the stop knob and the carbs appear to be in-sync. any other ideas? i really do appreciate the help!

 

[lastout]

Re: studddering at wot

bump