merc 20 hp 4 stroke carb issue

[marlattrr]

I am working on my 2011 Mercury 20 HP 4 stroke w/ carb.

I took the carb off and cleaned it good but did not replace the gaskets, everything looked good.

I put it all together and now the carb is flooding and gas is coming out of the overflow while im trying to start it. I took it apart again and check the float in it appears to be functioning and the need valve looks good to me.

Could the plunger be the cause of this?

 

[marlattrr]

I did replace a bad prime bulb during the carb cleaning. Not sure if related.

 

[nccatfisher]

Sounds like you are going to have to take it back off. I would pay particular attention to the needle and seat.

 

[marlattrr]

I looked at it and it looked fine and seemed to seal. Im going to just buy the rebuild kit and change all the gaskets and see what happens.

Could the plunger seal cause this? Thats the only seal that looks suspect. Not ripped but seems to be flat.

 

[marlattrr]

Replaced carb gasket kit and float/ needle valve. Same thing... im at a loss.

 

[RaisedByWolves]

What led you to tear it down to begin with?

Symptoms?

Is your tank vented properly?

You can check the needle and seat by removing and emptying the carb and letting it dry, then with the carb inverted and with a clean piece of hose lightly pull a vacuum on the hose and see if it leaks air.

Or alternately blow into the hose while lifting and lowering the float to see of air stops passing when the float comes to a rest.

Double check the bottom of the float is level with the carb body when held upside-down.

 

[marlattrr]

Thanks I'll try this tonight.

 

[marlattrr]

Still not working. Tried new gas. When i crank the motor fuel starts coming out of the over flow. If i spray carb cleaner in the intake i can eventually get it going with choke halfway on and some throttle but then had no water coming out of the water pump.

I just replaced the water pump impeller.

I just replaced the carb gaskets, minus the plunger.

Replaced both spark plugs.

I was going to give up and let the dealer fix it but they are back up 4-5 weeks. :x

 

[RaisedByWolves]

What plunger are you referring to?


Are you running the motor on muffs or in a bucket?

 

[marlattrr]

Running it with muffs.

The plunger for the prime on the bottom of the float bowl.

 

[RaisedByWolves]

Failing hard

 

[RaisedByWolves]

Running it with muffs.

The plunger for the prime on the bottom of the float bowl.

Throw them away and put the lower unit in a garbage can full of water.

Hopefully you didn’t ruin your new impeller.

How hard/much are you pumping the ball?

Can you hear fuel in the carb when your pumping the ball?


I’m not real familiar with the Mercs.

Pics?

 

[marlattrr]

I'm not even pumping the ball.

I will take the advice and throw away the muffs.

Everything i see online shows that the only cause for overflowing would be the float needle not seating. It looks like its seating, the needle is brand new and the float is set correctly.

I'm going to try to set the valve clearance. I havent done that since i owned the motor. Maybe that is contributing to the start issues and then fuel is just dumping out of the overflow because its not igniting?

The mercury 20 hp is actually made by tohatsu. So its a tohatsu 20hp.

 

[RaisedByWolves]

I doubt your valve issues have anything to do with it.

By ball I meant the one on the fuel hose.

 

[marlattrr]

Yeah the one on the fuel hose is always stiff like there's already pressure in the line. I barely ever have to squeeze it.

 

[marlattrr]

carb

 

[RaisedByWolves]

Yeah the one on the fuel hose is always stiff like there's already pressure in the line. I barely ever have to squeeze it.

Can you try a different tank/hose?

That seems off.

 

[marlattrr]

Does my gas line have a valve that keeps it pressurized? It always seems primed whem i put it on. I don’t usually even squeeze the pump.

 

[turbotodd]

leaky bowl gasket can cause overflowing.

 

[marlattrr]

Thanks. I did replace that.