Would it be necessary to replace the fuel filter to help pass emissions? I don't want to if I don't have to. Thanx. Also how would I know if the fuel vapor canister is bad?

 

You would get a check engine light if you had something related to the fuel vapor canister. The fuel filter is not a necessity to pass emissions. In order to be even an issue, it would have to be really clogged up enough to cause a shortfall in the air/fuel ratio on the fuel side. You would very much know if this occurred (you would likely feel it).

Main issues involving car and emissions testing revolve around the two A/F (air/fuel sensors) and the MAF sensor along with sometimes the IACV. A dirty MAF can throw off the balance and causing some pinging knock. A/F sensors get worn after time, but even then they will throw a code if bad enough.