why wont my mower run smooth?

Question

my mower was working fine earlier today, then i started this when i moved on to another lawn:
http://www.youtube.com/watch?v=aUwrGE6e0TE

i already cleaned the carb and air filter. i also changed the oil and cleaned and gapped the spark plug. i can see some debris in the gas tank, i think is coming off from the inside of the tank, but it never had a problem before.
what could be wrong?

cleaning the carb - i took it completely off and disconnected everything attached to it, then cleaned all the surfaces and blew out some grime that was caught up inside.

Answer 1

You probably have rust in your gas tank. Bits of rust flake off and clog up the screen on the end of the pickup tube. You need a new gas tank.

Answer 2

When you say you cleaned the carburator, do you mean you removed it and disassembled it? If not that is probably part of your problem. If you have debris in your tank it has to come out or it will continue to cause proplems. Gas tanks can usually be cleaned out by removing and flushing etc. Water in the gas tank will mess things up also. You can see water in the gas, it will look like a glob floating near the bottom of the tank.

Answer 3

You might also pop the flywheeel off and check the key for damage. If you hit a tree root or something hard, the key will shear itself and throw the timing off. New key only costs at 25 cents.