hi I have a Husqvarna yth 20-42 that won't start I've used clean gas I cleaned the plugs I've changed the fuel pump because the one it had wasn't working I replaced the carburetor.. it cranks good and only start for a second or two when I use starter fluid..it does not have a deck hooked up to it but I don't think that has anything to do with it..?? help pleaseeee johnny