1983 40hp twin cly Merc, help

[sea-ray steve]

I have a 1983 40hp twin cly merc.It starts and idels great buts starts skipping about a third throttle under load,put a kit in carb,kit in fuel pump,changed coils.Plugs are dry black.compression is 95and92.Am I right thinking its an air-fuel problem with the dry black plugs?Anyone have any ideas?thank-you

 

[shaw520]

Sound more like a gas/oil mixture problem,... 1983 so im guessing you're premixing ? Do you have correct oil/fuel mix ?

 

[sea-ray steve]

yes 50:1

 

[MH Hawker]

do you have the gray fuel hose

 

[Sylva-Ranger]

These engines sometimes have hi-speed portion defective on stator, that do troubles like that, exept dry spark-plugs.......

Did you try to squeeze priming bubble while running at hi speed to see what appens ?

​When you clean your carb, did you pay particular attention to clean the main-jet ?

 

[sea-ray steve]

put new grey hose on and have not used any ethanol.bulb stays hard while running.