3 HP Yamaha won't stay running.

[yammauser]

I bought a 3 HP motor and it starts right up but then stops and won't restart until later. Someone told me it needed a new impeller. I changed it out and it stays running little longer and I can see water spurting out but not much. Then it stops. I tried blowing up the water tube with an air compressor but no luck. I'm not sure if this motor is supposed to piss a stream. It has two holes on the shaft that spurt just a little water.