Can any body tell me if there is a way of testing the exhaust relief valve to find out if it's working properly? I bought the Johnson manual but can't find testing procedures in it. It starts easily with muffs but I took it to the lake twice and could not get it started when I backed the trailer in the water. The plugs got flooded the first time, so I replaced the plugs. I also removed the carbs and couldn't find any trouble there. Float hieght is fine, the needle is sealing properly - no wear on it at all, and there was absolutily no dirt in the bowls. I also put fresh type C gear oil in the lower end. I'm planning on replacing the waterpump & impellor over the winter but I'd like to find out if I have to do any repairs on the exhaust relief valve.