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Fs45 not starting

#1

A

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…


#2

StarTech

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.


#3

B

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 .


#4

StarTech

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.


#5

B

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


#6

A

aldumoul

StarTech said:
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.
Click to expand...
Good point. Gonna replace the carb.


#7

A

aldumoul

bertsmobile1 said:
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 .
Click to expand...
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.


#8

Fish

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.


#9

A

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!


#10

Hammermechanicman

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.


#11

A

aldumoul

Tried carb spray - to no avail. Emptied the fuel and put in new premixed fuel, and it didn’t help. Spark is good.


#12

Hammermechanicman

Hammermechanicman

You have a primary or secondary compression problem.


#13

B

bertsmobile1

Little trick here
A 1 second spray of carb cleaner own the throat of the carb is flooding the engine so you need to crank it several time with a wide open throttle in order to get a combustable air: fuel ratio in the cylinder
The amount some brain dead egos use on You Bube is almost enough to hydro lock the engine
Warming the plug with a hot air gun till it is too hot to hold in a bare hand also helps to get recalcitrent engines to run for long enough to properly adjust the carb.
Just done a 122LD back from another shop as being "unable to be repaired"
Had to back out the throttle stop 11 full turns which sort of explains why it would not start .


#14

Fish

Fish

If you have absolutely nothing, take a closer look at the piston with the muffler off. Also check the location of the flywheel magnets when the piston is at TDC.


#15

StarTech

StarTech

Once a two cycle flooded so bad that it is coming out of the muffler the engine must be cleared of the excess fuel. This done by removing the fuel mix and cranking until it run on the fuel in the crankcase.

But before doing this remove the muffler and check the piston and cylinder for scoring. If scored it is probably toast compression wise and no matter what you do short of replacing the PNC will not help.


#16

Hammermechanicman

Hammermechanicman

If a 2 stroke is flooded the easiest way to clear it is to remove the spark plug and turn the unit so the top of the cylinder is facing down and pull the cord about a dizen times. Gravity will help clear fuel from the crankcase.


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