Fs45 not starting

[aldumoul]

Cleaned the carb with my ultrasonic cleaner - to no avail. Then noticed gas coming out of the muffler so I looked at the gasket, and it is in poor condition. Reading, a prior post, it could still be a carb issue… also wondering if the muffler failure could create to much air in the cylinder? Needs to be replaced anyway, but good to know…

 

[StarTech]

I just don't understand why people keeps trying to clean a carburetor and then try reusing the old rubber parts. It like washing your feet and then putting back on the dirty socks.

 

[bertsmobile1]

Every time you open up a cube carb you replace the gaskets & diaphragms
This is why just about every brand does a G & D kit and a rebuild kit.
And no the engine is a one way device unless it is running backwards air can not go from the muffler into the combustion chamber while the unit is running
IF fuel is running out of the muffler then way too much fuel is entering the engine
Only three ways for this to happen
1) the metering diaphragm is split or holed
2) the metering needle is not holding the fuel back ( basically the same as a float valve failing on a mower engine ) .
Number 2 can be from crud in the seat preventing it sealing, a bad needle or way too much pressure in the fuel tank ( failed breather )
3) check valve stuck open on rotary valve carbs ( sorry too lazy to look your carb up )
If you sprayed carburettor throttle & body cleaner through the holes then unless it was a can of the very expensive Walbro carb spray then chances are you have destroyed the needle & every check valve as std carb spray softens the viton rubber used to make a seal so the carb is now trash as the check valves are no longer a replaceable service item .

 

[StarTech]

Bert if the metering diaphragm is hole or split the fuel will simple run out the carburetor metering diaphragm cover plate if the metering needle is struck open. Instead most times when the engine filling with fuel the metering diaphragm has stiffen and is holding the metering needle in an open position. And sometime the metering needle tip will develop a ring groove allowing fuel to bypass it.

Both Rotary and standard cube style carburetor vent one side the metering diaphragm to the atmosphere.

Very good point about cleaning these with carburetor cleaner and wire probes as both can destroy non replaceable check valves. This is why I only use soap and water in an ultrasonic cleaning machine.

Btw two cycle engines can run perfectly fine backwards if the ignition timing is right. I have personally seen on golf carts using two cycle engines to use this method for reverse. It is four cycle engines that can't.

 

[bertsmobile1]

yea you are right
i was not thinking right when i responded
so it has to be over pressurization or the needle stuck open

 

[aldumoul]

I just don't understand why people keeps trying to clean a carburetor and then try reusing the old rubber parts. It like washing your feet and then putting back on the dirty socks.

Good point. Gonna replace the carb.

 

[aldumoul]

Every time you open up a cube carb you replace the gaskets & diaphragms
This is why just about every brand does a G & D kit and a rebuild kit.
And no the engine is a one way device unless it is running backwards air can not go from the muffler into the combustion chamber while the unit is running
IF fuel is running out of the muffler then way too much fuel is entering the engine
Only three ways for this to happen
1) the metering diaphragm is split or holed
2) the metering needle is not holding the fuel back ( basically the same as a float valve failing on a mower engine ) .
Number 2 can be from crud in the seat preventing it sealing, a bad needle or way too much pressure in the fuel tank ( failed breather )
3) check valve stuck open on rotary valve carbs ( sorry too lazy to look your carb up )
If you sprayed carburettor throttle & body cleaner through the holes then unless it was a can of the very expensive Walbro carb spray then chances are you have destroyed the needle & every check valve as std carb spray softens the viton rubber used to make a seal so the carb is now trash as the check valves are no longer a replaceable service item .

The engine will not start. Gonna replace the exhaust gasket, and carb. If that doesn’t do it, time to hand it off to a professional.

 

[Fish]

If you are going to buy a carb online, make sure that the throttle cable end is the correct one, they made a change a while back.

 

[aldumoul]

Welp, I decided I’m not giving up yet. New carb, fuel filter, fuel lines. Carb adjusted. Used the same fuel I used to cut wood the other day and worked fine. What do you guys see as the next steps? It worked great 3 weeks ago…

thanks!

 

[Hammermechanicman]

I have seen E10 gas cause the o rings and diaphragms in cheap AM carbs to swell up and stop working. Try a little carb spray and see what happens.