F300 random shut off

[pstephens46]

No, the tech said he was gonna do some research and call Yamaha for some advise. I was giving him some time. Thanks for checking.

The frustrating thing was he ran it on 3 different occasions and couldn't replicate the issue with the computer hooked up.

He ran it in the water under load or at shop?

[RodWorks]

He ran it in the water under load or at shop?

On the water, even tried to replicate the issue by shutting it down for 15 minutes and then running hard after.

[RodWorks]

Tech replaced the VST relief valve (bad) and charcoal filter vent (had fuel intrusion prior and pieces of charcoal were falling out).

Still have the stall issue, after the first stall I primed the bulb (1 pump to firm), engine immediately stalled when getting on plane again. As before, I can immediately restart motor and run fine below 4000 rpm without issue. Seems that after running low rpm for about 15 minutes I can then go full throttle without stalling.

I asked about a loaner low pressure pump to rule out the issue, but none are available. May go the aftermarket route if he can't locate one to test with.

[RodWorks]

try a LP pump any updates?

Installed a new low pressure fuel pump today. Boat ran great full throttle for 6 miles. Stopped and fished, caught 4 pompano. While leaving, gave it about 75% throttle getting on plane and it hard stalls when it hits around 4000 rpm. Boat will get on plane with 50% throttle and run fine as long as I don't go over 4000 rpm. Pretty frustrated....

[99yam40]

if the VST is not running out of fuel when it stalls, (Does not need to be primed immediately after) then low pressure pumps should not be the problem or sucking air.
you need to find out if spark or fuel is what is shutting it down.
turn the key off immediatly after it happens and then try pumping the primer to see if the VST is low on fuel

[RodWorks]

if the VST is not running out of fuel when it stalls, (Does not need to be primed immediately after) then low pressure pumps should not be the problem or sucking air.
you need to find out if spark or fuel is what is shutting it down.
turn the key off immediatly after it happens and then try pumping the primer to see if the VST is low on fuel

It’s always one pump of the bulb to firm, I didn’t think the low pressure pump was the issue, but replaced it anyway to be sure. Thought maybe it could have been dying and pumping intermittently.

[RodWorks]

If feel like it’s spark that is the issue. Tech mentioned replacing the main engine relay.

It’s something to do with engine running hard and getting hot after shutting down for some time. Then running under heavy load.

[99yam40]

so does it run WOT at first start up cold?
for how long?
main relay would shut off the HP pump and injectors maybe also

[RodWorks]

Yes, I never have any issues on the initial run, I ran 6-7 miles today much of it over 5k rpm. Then after I stop and fish a while and go to run it happens.

[Mytoolguy]

Sounds like your sucking air in from somewhere. When was the last time you completely checked your water seperator?

[RodWorks]

Sounds like your sucking air in from somewhere. When was the last time you completely checked your water seperator?

I was changed about 60 hours ago. I'll take a look at it.

I can run full throttle on the initial run up to 20 miles...shut down to fish for 30 minutes and then it stalls when getting on plane afterwards. Doesn't make much sense to me except that something gets hot during the shut off period.

[99yam40]

I was changed about 60 hours ago. I'll take a look at it.

I can run full throttle on the initial run up to 20 miles...shut down to fish for 30 minutes and then it stalls when getting on plane afterwards. Doesn't make much sense to me except that something gets hot during the shut off period.

as I asked before, does pumping the primer bulb up tight right before that second run stop the problem from happening?

and when it does die, have you turned the key off immediately( so the lift pump cannot run) and then pump the primer to see if the VST is empty?

[RodWorks]

as I asked before, does pumping the primer bulb up tight right before that second run stop the problem from happening?

and when it does die, have you turned the key off immediately( so the lift pump cannot run) and then pump the primer to see if the VST is empty?

No, pumping the bulb before the second run makes no difference, still stalls.

I’ve also, primed the ball right after the stall and it’s just pump or two to firm. Engine will stall again right after that.

I’ve never found the VST empty, but replaced the low pressure pump anyway just to rule it out. I’ll try to turn off the key and check next time.

[99yam40]

if you prove the VST is not empty when it shuts down. then either the HP pump or injectors shut down or the spark goes away

[RodWorks]

if you prove the VST is not empty when it shuts down. then either the HP pump or injectors shut down or the spark goes away

I believe that’s the track I’m on, High pressure pump has been replaced, so it’s something cutting power to them I think. Main relay or ECU.

Gonna get the tech on the boat again and make the issue happen on YDIS. Hopefully it gets solved.