My buddy has a 210 Sea Ray with a 305 and TBI, it shut off on him now when you sit with the key on every now and then the fuel pump turns on and the injectors spray a few times but real jumpy then turns back off, then 2 minutes or so later it does it again. Without any real diag. it seems to be the ECM but any other input would be great. Thanks.

Is it a brand new boat?

It's a 2000

Try a new fuel pump relay first, Or their should be too relays by each other just switch them and see what happens.

Did that same thing, plus why would the relay make the injectors fire.

Your right I was thinking the fuel pump turns on and off, On it's owen and was thinking the relay was switching on and off all by it self. The way it works is you turn the key on and the ECM sees the power called wake up and the ecm wil turn the fuel pump for for 2 seconds to help prime the fuel system, And then the ecm will wait to see a puls referance from the pick up coil to the IGN control modual under the dist cap and that will tell the ecm "fuel injector driver" inside the ecm to fire off the injectors. So with that said the only things I could think of that would do this for some reason the ecm thinks it is seeing a pules from either movement in side the dist, For example the dist shaft/ rotor is moving sending a signel from the pick up coil to the modual both under the cap tellling the ECM to fire off, Or the modual is shorting out some how and sending the signel, Or the ECM has a short in side it at the "injector driver" sending the signel. I Hope this helps you out some, Good luck with it.

The first thing that comes to mind is the pick up which is in the distributor. Does the tach jump at the time that the injectors are firing?