My Poulan 260 pro starts and runs for 15 - 30 seconds and then dies. I have changed spark plug, replaced fuel filter, checked fuel lines. Any idea of what could be the cause?

Sounds like you made the Fuel line in the tank too short . OR the stone filter on the fuel line is not able to move about the Fuel tank to follow the fuel

The first thing to change is the fuel filter. If it still wont run, most likley you will need to rebuild or replace the carb.

They may be bad, but it could also be the check valve in the primer plate is bad.

Check the fuel filter, and muffler for plugging. Check the condition of all of the fuel lines. Fix or replace the primer pump. When you get it working right, push the primer quite a number of times to flush all of the old fuel out of the carburetor. Unless the carburetor is in trouble, you should be able to start the engine again. Hope this helps!

Check the fuel filter and muffler for plugging. Check the condition of all of the fuel lines looking for decay or other damage. Make sure the carburetor fasteners are tight. If still no help, check the carburetor lower chamber diaphragm for flexibility with no holes or other damage. Clean the carburetor with spray carburetor cleaner inside and out while you have it off of the engine. Does the primer bulb fill with fuel after several pumps? Did you check the spark at the plug--it should be blue and snappy. Hope some of this helps!

Sounds like a broken fuel line. I would first check to make sure you are getting spark by removing the spark plug and grounding the side of the plug on the engine and pulling the pull cord. Make sure you have spark. If you have spark then you will need to remove the cover so you can get to the carburetor and inspect the fuel lines for leakage or cracks. You should be able to watch the fuel flow through the lines while pushing the primer. Push the primer bulb and look for a broken fuel line.

I hope this helps you out.

INFO:
-Remove Carb and clean, you have a high speed fuel port clogged.

NOTE:
This would also be a good time to replace your fuel lines, Take photos before you start.

RECOMENDATIONS:
-Drain all fuel from the Saws fuel tank.
-Remove and REPLACE with a NEW spark plug.
-Remove and RELPACE with a NEW Air filter.
-With spark plug and air filter removed and fuel drained pull the starting cord many times 12 or so to ensure there is no fuel in the chamber and also check for a spark at the plug.
-RE-MIX WITH NEW FUEL your 2 cycle oil to the correct ratio in a clean fuel can. it is OK to dump some in the Saws fuel tank slosh around and dump out in an approved container for disposal.
-Hold off on putting back on the air filter until you have had it running.

Hope this Tip Helps.

R/
David

It is running in a lean condition. Continued operation like that can cause piston and cylinder failure.
I'd take it in for repair estimate ($10) at the local chainsaw seller/mechanic. Explain the problem you are having, Probably a leaking fuel line. I'd expect a repair and tune up about $40-60. Your saw will perform better and your arm will thank you. If tuned ask what fuel/oil ratio they used (should be 50:1) and affix a label to your fuel tank. HTH
Lou

Since it starts, it doesn't sound like an electrical problem, it sounds like it runs out of air. To test this, remove the air filter, start it and see if it stays running. If so, replace the air filter.

It could also be varnish or sludge in the carb bowl. This is best serviced by a technician if you have little mechanical prowess.

After sitting for 3 years, I would at minimum do all of this before I expected it to run ok:

1. Change the oil.
2. Replace the air filter.
3. Drain the fuel tank by removing the fuel line from the engine end (not the tank end).
4. Replace the spark plug.

If the above did not work I would drop the carb bowl and clean it, then add one ounce of carb cleaner to a full tank, and let it run (roughly if necessary) through the engine.

After sitting 3 years I would also replace the fuel line itself!

put a new spark plug in