motor won't run at low speed. If I pump bulb as tight as I can get it, motor will crank and run fine for a while. If I idle or run at low speed it will die and I have to pump the bulb again. If I run at mid range it runs good for a long time, if I run at full speed it will run a while then die. When I stop to fish, I have to pump the bulb again before I run. Have checked all the lines for air leaks