Twin F250's 2008 on Pursuit one engine shutting down but starts right back up.

[Rojoguio383]

Hello all Helpers, I have been chasing a shutdown problem for some time. The engine a F250 Std Rotation, 2008 model. The engines have temp sensors, right when the engine temp gauge gets to normal operating temp on both engines the Stbd engine shuts down. It will start right back up, run for a while then shutdown again. Each shutdown takes a little less time. We can drop back to idle, idle for a bit, throttle back up and run guessing about when it is going to shutdown again, throttle down and idle a bit, then run again. The engine will not shutdown. The Ignition switch was replaced, all relays in relay block, the second shift switch (Yamaha YDS said Switch issue), VST was pulled and inspected - perfectly clean, replaced serviceable parts while inside, also replaced fuel pump & harness as I read there were issues with shutdowns like what we are experiencing in just a little older models. 3 wire harness models. The shutdown is like you turn the ignition switch off, no sputtering, warning, alarm, and YDS logs nothing in events. I'm scratching my head, any thoughts?

[TownsendsFJR1300]

Sounds electrical...

Might want to check all your ground wires, battery wires and main harness to the engine(connectors and such for corrosion)

[panasonic]

You say that you can almost predict when the engine will shut down looking at the temp gage. Can you get someone to pump the primer bulb constantly just before it normally occurs to see if that makes a difference?

[99yam40]

vst is running out of fuel
restriction or sucking air is my thoughts

[Rojoguio383]

Thank you for your collective responses. Pursuit installed a priming station in this boat. When the engine shutdown I tried to prime / fill VST assuming myself it ran out of gas but VST was so full it took two pumps to feel pressure. It starts right back up, no filling the VST needed before re-starting. Being a USCG Chief Engineer myself the fuel system was the first go to but I could not find any problems. I can put pressure on the system and it does not leak down. 2007 and earlier F250's, Yamaha has a TSB concerning this very issue, the plug to the high pressure fuel pump would heat up and open causing a shutdown. This engine is not wired with the plug in question. Electrical is the direction I'm leaning, just hoping someone who has had this issue catches this post and replys with their cure.