Can't start my mower after replacing fuel filter

Sounds like the carb is dirty. if your carb has a fuel cup on the bottom of the carb remove it and clean it real well as well clean the fuel jet as well. a dirty fuel jet will not let the right amount of fuel to give it power. Make sure you have clean gas and the air filter is clean.

unless its a briggs I/C engine(orange) or a vanguard V twin (these use a vacuum driven pump) it doesn't have a fuel pump all it has is an inline fuel filter the fuel tank is just slightly higher than carb (gravity) , now it does take a special type of fuel filter (gravity type) and just any filter will not work , id use the factory replacement filter , briggs sells em lots of places

Possibly replace air filter . Check fuel is actually coming through carburetor. Check there is no dirt in fuel line or fuel tank. If old "dead" fuel renew with fresh fuel. Check spark plug lead is in good condition. As mower starts and then cuts out problem most likely to be fuel starvation. Hope these suggestions help.

First, drain the tank by removing the metal clip from the fuel line. Remove the air filter. Then remove the 3 bolts retaining the air filter holder. You will see the fuel line and the fuel filter. Squeeze the metal clips that hold the fuel line to the filter, and slide the line off. Replace filter with new one and reverse the process.
This is for a push mower. Good luck! Hope this helps.

If you left fuel in your machine for any amount of time I would consider a carb cleaning. Did you hit anything last time you mowed?
If so you may have sheared your flywheel key which times your engine. This will also cause a no start condition

Hard to start could mean a lot of things. Has the amount of pull required changed? IF it has then it might be something related to increased friction on the crankshaft. You either have spark or you don't. If you do then of course you need to change the gas first.

Here are a few tips to look at, I would first check your inline fuel filter to make sure its not clogged up. See Page 26 of the Manual for additional help.

http://www.husqvarna.com/ddoc/HUSO/HUSO2010_NAen/HUSO2010_NAen_YTH2348_532441716.pdf

PROBLEM
Will not start

CAUSE CORRECTION
1. Out of fuel. 1. Fill fuel tank.
2. Engine not "CHOKED" properly. 2. See "TO START ENGINE" in Operation section.
3. Engine flooded. 3. Wait several minutes before attempting to start.
4. Bad spark plug. 4. Replace spark plug.
5. Dirty air filter. 5. Clean/replace air filter.
6. Dirty fuel filter. 6. Replace fuel filter.
7. Water in fuel. 7. Empty fuel tank and carburetor, refill tank with fresh gasoline and replace fuel filter.
8. Loose or damaged wiring. 8. Check all wiring.
9. Carburetor out of adjustment. 9. See "To Adjust Carburetor" in Service Adjustments
section.
10. Engine valves out of adjustment. 10. Contact an authorized service center/department.

Battery required? Charge battery or replace. Replace air filter and spark plug. Dump out old oil and replace with 30w oil. Electric start may have a fuse blown. Dump out old gas fill with new with Stabile always added to gas. Try spraying starter spray in carb at air cleaner with filter removed. All mowers have a low oil sensor to prevent starting on low oil. Remove bowl from carb, should be full of gas. Pinch off fuel line with pliers or turn fuel valve off. Check float should be hanging down allowing fuel flow. Float up stops fuel flow.

Did you set the plug gap to specs?
Check fuel line filter.
Empty gas a replace with fresh fuel.

pull the flywheel and check if the key(latter models the flywheel itself will need replaced if stripped)is damaged. This is a possibility.