1990 Force 120 Getting Frustrated

[bigmatt14]

Hey guys,

1990 Force 120 with an ugly cough/sneeze problem. Compression is good. Decarbed twice. Reeds are good. Spark is good. New plugs. New carb gaskets. New transfer port gaskets.

Sputters like hell in idle. Less noticeable in high idle/in gear, but still there. Every once in a while while backing off the throttle, say decreasing from 3000 to 2500 rpm, it will cough/sneeze hard.

Any ideas before I part this chunk of metal out?

 

[shytownborn]

Re: 1990 Force 120 Getting Frustrated

maybe running to lean? open idle mix screws a bit and see if that changes anything

 

[bigmatt14]

Re: 1990 Force 120 Getting Frustrated

maybe running to lean? open idle mix screws a bit and see if that changes anything

Tried setting the mixture screws to spec. Tried opening them up a lot, tried closing them off, no change in the cough/sneeze.

Anything else?

 

[Josh P]

Re: 1990 Force 120 Getting Frustrated

double check your spark i had a coil going out that gave me a cough at idle it was only sparking half the time.

 

[92rslt1]

Re: 1990 Force 120 Getting Frustrated

Do you have a primer ball on it?

2 ways it can help.
It will tell you if you have a problem getting enough gas from the pickup(it will collapse or start too if there's a restriction in the tank)
It will stop the drain back if your check valves in the pump aren't working right.
Also, you could give it a little squeeze to see if it helps the bog or erratic idle your explaining.

Did you personally take the carbs off and go through them?
Are the carbs pretty well synchronized?
Did you check the timing advance?

 

[roscoe]

Re: 1990 Force 120 Getting Frustrated

It only does it when you back off the throttle?

Sounds like the linkage is hanging up, or not adjusted properly, not allowing the timing to back off as the throttle is decreased - creates a temporary lean condition which causes the "sneeze".

 

[bigmatt14]

Re: 1990 Force 120 Getting Frustrated

Josh P - Spark checked out again.

92rslt1 - I do have a primer bulb. It's fine. Tried squeezing it a bunch of times. Never soft, never any change in how the motor runs. Pulled both carbs, cleaned and sync'd well. Have not, however, checked the timing advance.

Roscoe - It sneezes/coughs violently and constantly at idle. When accelerating and at sustained higher rpm, it still misses, but not violently, smoothly if you will. During deceleration the miss is the same as the higher rpm until the rpm stabilizes again (say dropping from 3500 and stabilizing at 2000), at which point it will cough hard once or twice before continuing to miss smoothly again. When put back into idle, it will sneeze/cough violently and constantly, sometimes dying out all together.

What do I do? I'd hate to lose the motor, because there is no replacing it. Can't afford to buy a used outboard, let alone a new one. If the motor goes, so does the boat.

Any ideas? And worst case scenario, if I can't fix it, will the parts sell if I try to part it out?

 

[PaulO]

Re: 1990 Force 120 Getting Frustrated

Have you checked the timing?

 

[further]

Re: 1990 Force 120 Getting Frustrated

+1 on the timing

 

[bigmatt14]

Re: 1990 Force 120 Getting Frustrated

I have fiddled with the timing. I have not "properly" set the timing yet, but that will be my next step.

I'd appreciate some advice or guidance, as I haven't noticed a timing mark on the block. The world of 2 stroke outboards is still kind of alien to me. I'm much more comfortable with pushrod V8s.

Thanks guys.

 

[jason32038]

Re: 1990 Force 120 Getting Frustrated

Timing marks are on the flywheel. The timing pointer is on the top carb I believe.