1978 Evinrude 70Hp VRO. I rebuilt this engine 6 months ago along with new gas tanks, VRO pump and new oil tank and warning horn. Engine has run great every time since rebuild until Saturday. It is having a fuel problem I cant figure out. After 1-2 minutes at full throttle. (I dont know rpm because I cant find a tach for it) engine will slow to a stop and die. No missing or popping. I have two tanks and checked the obvious, no water in gas, hard bulb and I use fuel stabilizer year round. If I keep squeezing the bulb it will run or if I slow down to half throttle it will run. I also cleaned carbs and the fuel filters and purged the fuel system. I have the carbs with the fixed high and low speed jets, no screws to adjust. The only thing that has changed is the connector on the fuel hose tank side. It was used and dont remember before or after trouble started. Im going to buy a new one today. Would a bad check valve cause this? Can someone help out?