Need some help with a 351

Hi guys new here, just purchased a 23 sea nautique Pilothouse.

Engine shows 6hrs and seller stated it had a fresh motor in it.

Engine fired up easily and idled great but when we got it In the water it goes up to about 2k rpm and then dies. If you chop the throttle back to idle it will catch itself before dying and idles around 600rpm.

I’m unfamiliar with non fuel injected engines. Any pointers on where to start?

Fuel system does have a primer bulb like an outboard and pre start I primed that until hard engine starts quickly but after shutting it off that bulb is pretty flat, is that normal? Or could the fuel diaphragm pump (if there is one) be bad?


Thanks in advance