12.5 Spraying oil and gas from carb

TheRealHenry · Apr 13, 2016

Motor ran great, put it away after a cut.

Next time I tried to start it, it fired right up but then immediately died. I took the airbox off and tried again.

Again it fired right up but then started spitting a gas and oil mix out of the airbox and died.

What's going on here? I'm confused how this could occur especially after it ran fine before it was parked.

pugaltitude · Apr 13, 2016

TheRealHenry said:
Motor ran great, put it away after a cut.

Next time I tried to start it, it fired right up but then immediately died. I took the airbox off and tried again.

Again it fired right up but then started spitting a gas and oil mix out of the airbox and died.

What's going on here? I'm confused how this could occur especially after it ran fine before it was parked.

If its oil in the air filter then it sounds like your head gasket has blown between the cylinder and the valve chamber.
Supply the model, type and code of engine to check its that first.

Tinkerer200 · Apr 13, 2016

Didn't check the oil level before starting did you? Float needle probably leaked filling the crankcase with gas

Walt Conner

TheRealHenry · Apr 14, 2016

Tinkerer200 said:
Didn't check the oil level before starting did you? Float needle probably leaked filling the crankcase with gas

Walt Conner

I believe this is exactly what has happened. I worked on the mower a little more yesterday and found the oil is full of gas.

Do I need to rebuild the carb? I'm very unfamiliar with the 12.5. Mower was bought second hand.

bertsmobile1 · Apr 14, 2016

Yes you will need to change the oil twice to gte rid of the gas
You will need to rectify the leaking carb by fixing the float needle.
how you do this will depend upon what motor & what carb you have.
Thus Plugs request for numbers.
You might also like to fit an in line fuel tap between the gas tank & the fuel pump or fuel filter depenfing upon the model.
Belts and braces approach but $ 5.00 says a lot of stuffing around.
Note you will still have to clean the carb or the engine will flood while you are driving but at least in future you will not need to do a double oil change.
When you get it running , check the dip stick tube and the crankcase breather in the air cleaner.
You might need to run it for 1/2 hour or so to clean the crud out.
If it blows a lot of oily fume into the air filter or smoke signals from the breather tube then the head gasket is gone.

upupandaway · Apr 18, 2016

As Berts said, yes it is a carb leaking problem but the fix may be simple.
These carbs on 12.5's i have come across that clean and replacing the float needle does not rectify the problem and i have resorted to adding a shutoff valve as a result.
If i were you, change the oil then take it for a spin and cut grass to see if it does indeed flood while running thus need rebuild\clean carb or else KIS and add a shutoff to prevent this again.
For myself,clean\replace never solved my problem so valve it is.

TheRealHenry · Apr 19, 2016

pugaltitude said:
If its oil in the air filter then it sounds like your head gasket has blown between the cylinder and the valve chamber.
Supply the model, type and code of engine to check its that first.

Model: 28U707
Type: 1113-E2
Code: 030516Z0

Can someone explain what exactly the shutoff valve would do that will rectify the problem?

pugaltitude · Apr 19, 2016

Fuel shut off valve or fuel tap will stop fuel flow when not in use.
The needle in the carb dont always seal which then
allows fuel to leak past and fill engine up with fuel where the oil is supposed to be.

TheRealHenry · Apr 19, 2016

pugaltitude said:
Fuel shut off valve or fuel tap will stop fuel flow when not in use.
The needle in the carb dont always seal which then
allows fuel to leak past and fill engine up with fuel where the oil is supposed to be.

So simply by installing the valve and keeping it off when the mower is not in use, I can fix the problem?

bertsmobile1 · Apr 19, 2016

I will not fix your current problem but it will prevent it hapening again.
You might be lucky and have not done any engine damage.
You won't know this till you have cleaned out your engine and tried it .

12.5 Spraying oil and gas from carb

More options

TheRealHenry

Forum Newbie

pugaltitude

Lawn Addict

Tinkerer200

Well-Known Member

TheRealHenry

Forum Newbie

bertsmobile1

Lawn Royalty

upupandaway

Well-Known Member

TheRealHenry

Forum Newbie

pugaltitude

Lawn Addict

TheRealHenry

Forum Newbie

bertsmobile1

Lawn Royalty

Footer Links 1

Footer Links 2