I found this about the Emerald Plus 4000 BGE
AIR FILTER
ONAN - P/N 140-2379
WIX - P/N 42362
NAPA - P/N 2362
FRAM - P/N CA8235
OIL FILTER
ONAN - P/N 122-0645
WIX - P/N 51374
NAPA - P/N 1374
FRAM - P/N PH2870A
FUEL FILTERS
BGE - Spec ONAN P/N WIX P/N NAPA P/N FRAM P/N
A-E (these model generators never equipped with fuel filters)
F,G 149-2279 none none none
H 149-1353 33046 3046 G22A
J-P 149-2333 33933 3933 none
SPARK PLUG
http://www.autolitecatalog.com/Application.aspx?b=A
Let me know if anything is wrong so I can update my information