mercury 850 or 85hp stumbles at idle and wont plane boat

[snake91876]

I have been messing with a mercury 70s model 85hp blue band with two one barrel carbs. The motor was running good and sat for 10 years parked , wiring was deteriorated. Rewired boat and put new plug wires, plugs, rebuilt carbs , fuel pump diaphrams, replaced timing belt, cleaned distributor cap. i didnt move any timing on distributor.Boat will run but keeps a high idle, when i bring the idle screw down on distributor it will start to level off to idle and gets ruff and just abruptly in one jolt shuts off i guess kinda like a lean sneeze but i dont hear the sneeze from carbs. I have the floats with the top lever level to body of carb. I did adjust these as they were letting fuel blow through carbs. Could i have the bowls too dry now. The motor is on small starcraft 15ft fiberglass it will take off but barely plains and just doesnt have that ump to go like it should. I couldnt get it to transistion on plane but richened idle circuit and it plained after running several hundred yards. ANY IDEAS!!!!!!!!!!!!!!

 

[Gomer50]

Re: mercury 850 or 85hp stumbles at idle and wont plane boat

Take a compression test.I use mid grade or super gas (runs alot better) and bring your max advance timing down to 21 degree's BTDC @ WOT.Still would recomend doing a link and sync.Run a little seafom thru your fuel system it will take out all the carbon build up,gunk etc. that might have accumulated over the years sitting.It will also free up piston rings should they be stuck.Compression check first.Good Luck..