87 Ranger, fuel filter

Have a 2.9L with fuel injection, with inline canister style fuel filter.
I removed the canister to find no filter cartridge, and a small ( 1/4")
O-ring laying in the bottom of the canister. How common is it, to not have a filter in the canister, and where did the O-ring come from? :confused: :banghead:

the filter is foward of this canister, i did the same thing,, it is a standard type filter with the plastic quick locks

I put a filter in the canister. Wonder if I should take it back out. By the way, it seems I have 2 fuel pumps also. One in the tank, one in-line. Not sure how to check if the one in the tank is working or not. I'm not getting fuel to the moter, since the day I removed the fuel from the tank. That's when I found the 2 fuel filters.