My boat will not stay running.When you prime the fuel it will run for about a minute.?

Question

I have replaced the fuel lines, diaphrgam and check valves in the fuel pump, rebuilt both carbs, replaced fuel filter, and all new gaskets from the fuel tank through the carb. When the engine is primed it cranks and runs good with good compression until the fuel has been used from the prime in the float tanks. I noticed yesterday in the while in the water that no water in coming from the weep hole. Could the engine be geting to hot evaporating the fuel in the fuel pump? THe engine is a 1977 or 79 outbaord 2 cycle mercury 650, 65hp. Please Help?

Answer 1

check your powerpacks this happened with my johnson 35 i know it sounds wierd but it worked for me

Answer 2

All good answers so far, I just will add one thing. You failed to say what kind of tank you have, so I'll assume it is a permanent mount tank for arguement. If it is, you may just have a partially plugged anti-siphon valve. this would allow you to pump the primer and get enough fuel, but the 65hp doesn't have enough pump to pull past it. The valve is mounted at the tank where the fuel line connects. it looks like a normal hose barb, but has a ball and spring in it. They are used in internal tanks to avoid filling the bilge if a fuel line breaks. We see it all the time.

Answer 3

the first thing i would check would be the fuel bulb and the vent  sounds like you covered everything else  it could be that with your   old motor that its not creating the vacuum needed to run the pump even with a motor that has good compression  you could have lost a seal on your intake or even on the crank case itself u need to see what kind of vacuum presser the motor is pulling

Answer 4

Have you checked the tank vent? Try running it with the fill cap off and see if thats the problem. Also the check valve in the primer bulb can go bad.