just got a boat with a 01 115 johnson, runs great until about a quarter mile up river and it starts surging, acts like its running out of gas, i had my wife drive today while i squeezed the bulb and it started running fine again until about a quarted mile after i quit pumping the bulb, i figure the carbs are starving for fuel at that point, i have already checked the fuel filter, it had a little trash, cleaned it out, went back to the river made no difference. i figure its gotta be a weak fuel pump. does it sound like im on the right track? just want some other opinions before i go buy one. thanks