Carb ajustment question on OMC engines

[jerrysharrett]

I have a 1990 Evinrude 3-cyl and I need to adjust the air/idle screws. How is the best method?
TIA

 

[emdsapmgr]

Re: Carb ajustment question on OMC engines

Very slowly. All three carbs are connected together inside the block. So, turn one of the 3 idle screws only 1/2 turn and wait a minute for the engine to "normalize." What you do to adjust one, affects the other two, so The adjustment of these carbs will take some time, doing it slowly, deliberately. It's sort of a pita.. Even after you get it "optimized" it may not idle perfectly-it's a 3 cyl thing.

 

[bob johnson]

Re: Carb ajustment question on OMC engines

1989 manual says that the initial setting is 2.5 turns from seated.... and that when adjusting from there turn 1/12th turns at a time and wait 15 seconds....the motor needs to be in the water , in gear....they actually say tie the boat to the dock! ha ha


bob

 

[emdsapmgr]

Re: Carb ajustment question on OMC engines

Follow Bob's directions. They are correct. As you can see, it will take some time to really dial this in-considering the small increments of adjustment. I'm still not happy with the way my 92 idles...

 

[WernerF]

Re: Carb ajustment question on OMC engines

My 1989 manual says NOT to tie the boat to the dock or trailer but to leave it unrestrained...

It's good to have a tach that clearly shows the actual RPM around the low end. Some multimeters are able to measure frequency and can be used. When you come close to the optimal setting, the RPM differences become tiny.

Test your final adjustment by running the engine at/near WOT for some minutes and then immediately returning to idle in gear. The engine shouldn't stall, sneeze or backfire. If so, at least one carb is too lean.

Idle RPM is 700...800 in gear. When the weather is cold keep to the high side. RPMs will drop a little in hot weather.

And yes the 3cyl. could idle better. Loopers do everything better than crossflows except idle.

 

[bob johnson]

Re: Carb ajustment question on OMC engines

My 1989 manual says NOT to tie the boat to the dock or trailer but to leave it unrestrained...

It's good to have a tach that clearly shows the actual RPM around the low end. Some multimeters are able to measure frequency and can be used. When you come close to the optimal setting, the RPM differences become tiny.

Test your final adjustment by running the engine at/near WOT for some minutes and then immediately returning to idle in gear. The engine shouldn't stall, sneeze or backfire. If so, at least one carb is too lean.

Idle RPM is 700...800 in gear. When the weather is cold keep to the high side. RPMs will drop a little in hot weather.

And yes the 3cyl. could idle better. Loopers do everything better than crossflows except idle.

you are correct, I MISSREAD the manual....it does say Must NOT be tied to a dock..... Iguess my mind ran ahead, and read what it wanted ha ha


bob