Poulan 46cc chainsaw. Part called a crakcase isolator (#34 on parts diagram). Where does it actually go? put it in the air filter, but interferes with the butterfly valve to carburator.

SOURCE: Poulan chainsaw 46cc 20" chain

You normally have 3 screws - idle speed - slow running and fast running.
First take care as if it runs faster than idle speed that chain will be whipping around also.

Second you have to determine what is the problem. Is it faulty at low speeds or high speeds ? or won't it idle.
If it has turn stops fitted to the screws you only have a small adjustments either way.

If it won't idle, try turning in the idle screw a half turn - until the chain just starts to move slowly.
If its dying at slow speeds, get is going and slow turn the slow screw out until it starts to run a bit rough then turn it back in to the point where its running smoothly.

Bad fast speed can be caused by simple things such as a blocked muffler ( insects too - I had one blocked off by a mudnest wasp) - otherwise get it running at full and adjust the fast screw as per the slow one - out till its rough then back in slowly until its smooth.

Suggest before all this tho that you get it running with the cover off the carby and then give it a good squirt of carby cleaner first - it may just clear out any 'poop' thats there.

(Have faith even tho I have a Poulan with a carb that refuses to run on anything but carby cleaner. I have pulled it apart a few times and renewed all the perishable bits buts its a real pig)

SOURCE: Poulan Pro 295 46cc chainsaw that won't start

Does the spark plug get wet with fuel when pulled through? If dry, try spraying a little starting fluid in the plug hole and reinstall the plug. If it pops at least once, you have fuel delivery problems--look for hardened/ cracked fuel lines. Clean the muffler arrestor screen. When the muffler is off, check the condition of the piston skirt and cylinder wall for deep scoring or obvious wear. Make sure the primer button (if equipped) is filling with fuel when pumped a few times. If it doesn't, make sure the bulb is not hard or cracked and check the lines going to and from it. Check the carburetor bolts and nuts for tightness. The fuel filter in the tank could be plugged, fish it out and check. If you have checked all these items, it may be time to clean and rekit the carburetor. Hope this helps!

SOURCE: I Need Diagram of Fuel Line Hookups For a Poulan

The line at the rear of the fuel tank with the fuel filter is the main feed line to the carburetor and connects to the upper nipple. The lower nipple on the carburetor goes to one of the primer ports, and the other primer port goes back to the tank, which has no filter on the tank end. On the primer port, it is cut and try--remove the tank return connection and leave loose. Place the main fuel line on to one of the primer ports and try to pump fuel into it with several pumps.Make sure the filter in the tank is not plugged. If nothing, shift the line to the other port of the primer and try pumping again. When successful, remove the main fuel line and return it to the upper carburetor port. Run a new line from the lower carburetor port to the active primer port and try to pump fuel again. If it won't pump fuel, reverse the two connections at the carburetor and try to pump again. If still nothing, there is trouble within the carburetor which should be cleaned with spray carburetor cleaner and maybe re-kitted. When you can finally pump fuel through the carburetor, then attach the tank return line to the open port on the primer bulb. Hope fully, the engine should run at this point. Hope this helps!

SOURCE: Poulan chainsaw model #2550 Serial #

Check the fuel filter, air filter, and muffler for plugging. Check the carburetor lower chamber diaphragm for flexibility and no damage. Also check the needle valve tip that the diaphragm controls for any damage or wear. If still flooding, turn both needle jet screws CW to stops (lightly), the back each out CCW 1-1/2 turns. This is a basic setting which should allow the engine to start and run.
Start the engine and allow to warm up. Pull the throttle full on and adjust H needle CW till the engine starts to speed up, but still 4-stroking. Correct adjustment is when the engine 4-strokes unloaded, but immediately 2-strokes when cutting. Release the throttle and adjust L needle CW for better idle but allows the engine to 'follow the throttle'. Adjust idle speed screw so that the chain stops turning, but the engine continues to run. Hope this helps!

SOURCE: I need a routing of the fuel lines from filter to,

There are two holes in the fuel tank, it does not matter which line goes to which hole. The lines should run as follows: One line from the tank should have a filter on it, connect this line to the primer bulb and put a mark on it with a sharpie. Another line should run from the bulb to the carb, and the last should run from the carb back into the tank. After they are all in place, pump the bulb and watch the gas in the marked line. If gas is flowing from the tank through the marked line into the bulb and on to the carb you are done. If gas is flowing towards the tank in the marked line or not at all reverse the two lines on the bulb and you're done.