9.9 Yamaha loses prime

[Money Pit 3]

I have a 1989 9.9 that loses prime. It will run all day if I squeeze the primer bulb every few minutes.I have replaced all the fuel lines from the water seperater to the motor,put in a new fuel pump.I tried running on a seperate tank and it still does the same thing.A mechanic I know thinks the camshaft may have a flat spot so its not moving the fuel pump.My question is how big a job would it be to put in a new camshaft or could I put in a electric fuel pump instead

[boats.net]

Replacing is not a simple job but can be replaced. It's usually an air leak in fuel lines or connections that causes that.