Oil injection

recently purchased this boat with a 150 mercury outboard. It has a large abt 2 gallon oil tank under rear seat and a small tank on engine. I put a gallon of oil in the tank under the seat. Installed a new cap on the engine tank. have not had the boat out yet and just started it at idle on muffs using a 6 gallon premixed tank. Today I checked oil tank and it has maybe a quart left in it. I noticed oil under cover and found a small line going from small tank to oil pump , I think,it was disconnected. could all the oil siphoned out of the tank under the seat? I found a good amount of oil on ground under engine. Not sure if I should add another gallon and try again now that i reconnected the small line. Any help would be appreciated.

After further investigation and reading the book I find the line that was disconnected was from the oil injection pump discharge. fixed that. took the boat out and ran good on pre mix tank. gallon of oil in remote tank and half full tank on top of engine. Ran 15 min and came back home. oil injection works if there is oil in the tank on top of the engine but there is no air coming from the engine to the remote tank. nothing in the book answers that question. if there is no air the remote tank will go empty and I am in trouble. what should I check now.