Force 120 engine cuts out at low speeds

[smatthews1999]

Hey guys,
I have a '96 120hp Force engine, and I'm very happy with it. It runs great - more or less. The only problem I have with it is it doesn't like to run at 'no-wake' speeds. It runs rough and will cut out and die. The problem seems to be worse after the engine has warmed up. Any ideas what it might be? Timing or idle adjustment?

Thanks,
Sam

 

[steelespike]

Re: Force 120 engine cuts out at low speeds

Speaking generically if the carbs have low speed mixture adjustment screws.These may appear on the fromt of the carb.They need to be adjusted with the motor warm and idling in gear.clockwise leans the mixture counter clockwise richens it.

 

[gregmsr]

Re: Force 120 engine cuts out at low speeds

De-carb and new plugs helped my 89 125hp. But still runs a little rough at low speed. Havn't tried to adjust low speed screws yet.
How lean is too lean?

GM

 

[baxtr]

Re: Force 120 engine cuts out at low speeds

I don't mean to be the one bringing the ugly date to the party, but mine did that and it turned out to be cylinder 3 no compression, broken rings, and partially broken piston crown.

Obviously try all the above first, but throw in a compression check. Mine would fly fine at WOT but would shake and want to die at low speed.

rebuild fixed it

 

[steelespike]

Re: Force 120 engine cuts out at low speeds

De-carb and new plugs helped my 89 125hp. But still runs a little rough at low speed. Havn't tried to adjust low speed screws yet.
How lean is too lean?

GM

When adjusting the low speed mixture adjust to the best setting then go slightly toward rich but not so much it changes the idle.Generally speaking too lean can make it stumble when you hit it to accelerate.
By all means give her a compression check.Should be
at least 100 psi and within 10% cylinder to cylinder.

 

[smatthews1999]

Re: Force 120 engine cuts out at low speeds

Thanks guys I will give that a try and report back.