John Deere La108 only runs with air intake blocked

[al new life]

My john deere idles beautifully when I cover the intake manifold, I have to do the same thing to start it
does anyone know what is the cause so I can make repairs ?

Thanks Al

 

[bertsmobile1]

the engine is starving.
Either you have an air eak between the engine & carb
or the carb is not passing enough fuel into the engine.

Pull the fuel line off the carb & put it in a catch jar.
Crank the engine and look for a full flow of fuel.

If there is plenty of fuel getting to the carb then pull the carb off and clean it .

 

[ILENGINE]

i suspect the carb main jet is clogged and will need a good carb cleaning.

 

[al new life]

Thank you gentlemen for all responding, I will bring you up to speed
I went and purchased a rebuild gasket kit, and installed it, but first I gave the carb a good cleaning with cleaner including all orfices
when I reinstalled the carb, I checked for good gas flow like suggested with a jar, and the flow was good
Now the mower will not fire at all, and I am seeing some raw gas coming out of the exhaust pipe, the battery is on a currently on a charger, since I ran it down
The mower has a briggs and straton engine if that helps
The spark plug is new, and the air cleaner seems to be in good shape

please advise, if you can see what I am missing or if I created a new problem without knowing I did something wrong

Regards Al

 

[motoman]

Some miscellaneous thoughts... Originally your hand became a choke butterfly , enriching mixture. Then it was starving as noted. Now with raw gas perhaps needle seat problem or float setting?

 

[al new life]

I was thinking (hoping) the float was malfunctioning, I will open carburetor again and keep trying to win this battle
I get a great sense of accomplishment whenever I can achieve success, so I will solicit all the input I can

thanks again

 

[bertsmobile1]

Thank you gentlemen for all responding, I will bring you up to speed
Big snip
Now the mower will not fire at all, and I am seeing some raw gas coming out of the exhaust pipe, the battery is on a currently on a charger, since I ran it down
The mower has a briggs and straton engine if that helps
The spark plug is new, and the air cleaner seems to be in good shape

please advise, if you can see what I am missing or if I created a new problem without knowing I did something wrong

Regards Al

Is this liquid gas or vapour ?
Liquids do not burn, only gasses burn so if liquid is dripping out out of the muffler then the float is stuck and it is flooding.
Pull the carb off connect the fule lines to it and crank the engine.
no fuel should come out of the carb.
If you have a vacuum that blows, hold it to the intake of the carb and look at what comes out, should be a fine mist of fuel .
Note if all is well this will be a very flamiable fuel mist , so no sparks, cigarettes, naked flames etc.
If all checks out OK, try a fresh plug.
modern fuel which is nothing like petrol is highly conductive at cylinder pressures so can short out a plug in no time flat.

If fresh plug makes no difference check the flywheel.
There should be a 1/2 square slot in it and another in the shaft.
If the key is intact they should line up to form a square.
crank the motor a few times and see if it changes

 

[Mikel1]

Just checking but do you still have spark?

 

[al new life]

Thank you for all responses, it has definitely helped me stay on the correct path of action
As it turns out while I was cleaning the carburetor, the main jet came out and I was not aware, that I had lost it, (it took me two days to figure out it was missing)
and I believe that is why all the gas was passing thru the carburetor, and out the exhaust,
The plug is definitely fouled now, and I have had to order a new main jet, the new part is three days away
I will keep everyone informed after I have opportunity to install new jet
I"m sure y'all can tell by now that this is the first time, I have taken apart a carburetor

thanks again

 

[ILENGINE]

Don't feel back even seasons techs have been known to loose that jet.