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Not sure what to say other than its fuel starvation, if not already done replace the fuel filter in the tank, if no better i would suspect a massive air leak, so replace the crank seals, if there is no primary compression in the crankcsae fuel will not pull through the engine, good luck.
This is fuel starvation ( it is running too lean ) if it has been stood from last year with the same fuel in , the fuel may have gone stale and bloced the jet in the carb, keep priming and starting this may eventualy clear the carb, if not the carb will have to come off and clean through, ley us know if you need help servicing the carb.
Did you check/replace the fuel filter within the tank? Did you re-kit the carburetor when cleaning it? The lower diaphragm fails every so often, but the pumper diaphragm in the upper chamber usually isn't included with a rebuild kit. The lower diaphragm is responsible for maintaining proper fuel quantity to the jets and should be flexible with no holes or tears. There is a very small screen that is located in the passage from the upper chamber to the lower chamber. Check the impulse passage behind the carburetor which delivers pressure pulses to the pumper chamber for plugged holes or torn gaskets around the passage. Go to: http://www.drystacked.com for a 12 page article on Walbro brand carburetor theory and troubleshooting. This information applies in general to other brands of carburetor. Hope this helps!
if theres nothing wrong with it you should close the choke between half and quarter (depends on the engine) and gently rev the engine bit by bit till it warms up, you will find the revs increase with gas to a point but if you give it any more gas it will start to stall and cut out, you have to wait for it to warm up - by keeping the gas at the sweet spot where you get best revs without it cutting out - then slowly increase gas pressure as the engine warms up - you can press it a little bit more bit by bit as the engine warms up and the combustion gets better - eventually you will be able to press the gas fully kin and the engine will just run but sound bogged down or gasping for air - this is when to open the choke to the RUN position (or fully open) --- it's now ready to use.
To restart a hot engine when it's been stopped :
1 Prime the engine - 3 squirts -
(you wont flood it - plus it lubricates the top of the cylinder with fresh 2 stroke and is good for the engine)
2 Hold gas a quarter way open
3 Pull cord!
as soon as it fires give it an extra squeeze of gas to give the best chance of a clean start.
From your description, it sounds like your carb is running too lean. Make sure the spark arrestor screen is free of carbon build-up and the air filter is in place. Warm the saw up. With the saw at idle, adjust the Low adjustment screw to slightly enrich the mixture. If you turn it to run the fastest possible when idling, it is too lean. When the Low setting is right, you will be able to increase the RPM without it dying. If the High setting is way too lean, it may also die when you open up the throttle. If you run the saw too lean, it willl overheat and sieze.
OK - let's work through this. If you need choke all the time then the mixture is too weak when the choke is off. Putting the choke on literally chokes off the air supply to the engine by lowering a small shutter across the entrance to the carburettor. That means either there is too much air getting to the engine (don't see how!!) or too little fuel. So, how do we get too little fuel? You could check for this as follows;
- before we do anything tricky let's check the obvious things - is there a fresh fuel mix in the tank? Petrol does go off, especially if there is 2 -stroke oil added to it. If it's over a month old from the pump mix up a fresh batch. Is the idle speed set too low so the engine stalls when the choke is knocked off? You can see this screw to one side of the carburettor (you need to remove the top lid in front of the handle on the chain saw, and then remove the air filter to see it). Turn the screw half a turn clockwise to speed the engine up. Be warned - if the engine starts it will run faster than normal and that means the chain may start to spin around. Also - check that the chain brake is off (i.e. the safety lever is pulled backwards, and that the chain is free to move BEFORE you attempt to start)
- is the fuel filter blocked? To get to this, make a wire hook (e.g. thick fuse wire) and gently hook out the fuel filter that's sitting at the bottom of the fuel tank, and take a look at it (be gentle - you can damage the gauze if you are clumsy). Does the gauze look clear? I.e. if you dip it into petrol it will freely run into the filter and of course drain out when you lift it? If not, replace it.
- next stop - are the jets in the carburettor set right? I don't have a service manual for this (and I know the manual says unhelpfully "return for service") but basically you will have seen two holes on the side of the chain saw (below the handle) two small 0.8cm holes; one marked 'L' (for low speed) and the other 'H' (for high). Put a fine flat screwdriver down the L hole and feel for the slot of the low speed jet. Once engaged turn it out half a turn and this will enrich the mixture - if this seems to help and you can start the engine then adjust the L jet in or out until the engine is idling comfortably. If it idles too quickly then you can also turn down the idle screw (see previous paragraph).
- no luck still? Well, it could be fuel pump or a blocked jet in the carburettor but this really is a 'return to the service centre' task!