pnichols, We have the little Onan Micro Quiet 4000 generator (2007 vintage)! The filter is located on the end of the unit, near the manual start button and breaker area. The filter is somewhat hidden by a rubber boot/plug in the lower part of the generator housing. The “dead giveaway” is the 3/8” (I think) rubber fuel line routed up from it toward the RV frame. A 9/16” deep socket makes removal easy. It’s a little awkward to access, but a 9/16” open end wrench, and a little patience could get the job done! hope that this discription was somewhat clear. Among my many shortcomings.....giving directions may be my “greatest”! :B memtb