F70 stalling when under way

[CountryRN]

I have a F70 that has recently developed a stalling problem when under way. Occurs when the boat is cruising at 20 mph or more. The problem does not occur at slower speeds.
The motor will shut off dead as if the safety switch was pulled and will immediately start again when ignition switch is turned. It runs smoothly without any shuttering or spark knocking. The fuel bulb is full and battery connections are good.
I had a mechanic run a diagnostic on the motor, but there are no coded saved.

I anyone has an idea what the issue may be or has had a similar problem, please let me know.

Thanks.

[TownsendsFJR1300]

Try cracking the fuel tank cap loose while under way.

If not venting, it can act exactly as yours is, literally running out of gas with a full tank.



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[99yam40]

I would monitor rail pressure to see if that is going away when it dies.
that would tell if the pump in the VST is turning off or running out of fuel to pump.
if rail pressure stays in spec, then you look at spark or injectors stopping dumping fuel

[CountryRN]

As an update to this issue, I removed the safety kill switch to rule out a short that could ground the motor out from the switch. The fuel line, water separator, fuel filter and VST filter have been changed. A new low pressure fuel pump has been installed. Like before the motor cranks immediately, idols smoothly and accelerates strong. The crazy thing is that it will run at wide open throttle, but if attempting to cruise around at mid throttle, it is going to die.
Just like before it will crank right up before the boat stops moving.
If anyone has an idea what could be wrong, please share.

[99yam40]

you still have to find out if it is spark or lack of fuel that is causing the motor to die.
test things