Sudden loss of power

[tdsull]

While cruising yesterday from St Pete to Sarasota in a moderate chop and 15 knot head wind we had a sudden loss of power, boat stopped cold. Tried restarting, nothing. Dropped anchor and started checking everything. Then my 5 year old walks over to the helm and turns it over on the first shot.

Chart plotter came online slowly but not before we ran aground. For my Florida counterparts we were off Anna Marie island heading into the ICW for the first time. Luckily we were going 3 knots and it was sandy. The strong head wind oriented the boat in the right direction and I goosed it off the sand. Phew!

We took it easy the rest of the ride ( 2.5 more hours) and had no issues with power. The tachometer never kicked back on.

What would cause a sudden and complete loss of power like that? Do we think the three rounds of puke down below from the kids fouled anything? I will not get them 50 cent frostys again before a lumpy ride.

[Tree]

That’ll be your stop solenoid that has shorted out. Makes for a brown trouser moment when it does that eh?

I’ll never forget when mine tripped out at 19knots. Nearly threw me over the dash!

I don’t have a picture but I know there is one on the forum. Just search for yanmar stop solenoid.

[Tree]

It may also be known as a stop relay.

[tdsull]

Perfect. I think I still have an alternator issue as my 4d battery from 2017 was reading 11 volts this am.

[RobS]

Chart plotter came online slowly.

This comment leads to an issue with the boat's DC system, not an engine issue.

[tdsull]

Agreed. I do also think I have an alternator issue as well.

[RobS]

Agreed. I do also think I have an alternator issue as well.

Yes, I consider the alternator more part of the "boat system" than that of the engine, if that makes sense....

[tdsull]

Tree, I found the relay part # in previous posts, super helpful.

When you replaced yours did you also replace the solenoid? Relay is $25, solenoid is $250.
I have injectors, valve adjustment and a timing belt coming due this month so I am being a bit careful.

[Norseman]

. I have injectors, valve adjustment and a timing belt coming due this month so I am being a bit careful.

How much do you expect, or budget for the above?

[kerrye]

Does the stop solenoid require electricity to keep the engine running? If so, an electrical failure which cut off the power to that solenoid would stop the engine.

[Tree]

Does the stop solenoid require electricity to keep the engine running? If so, an electrical failure which cut off the power to that solenoid would stop the engine.

Yes it will do. Via the relay. Pull the relay first before delving deeper and you may find it is pretty well corroded. For some reason, yanmar leave these hanging loose right below the oil cooler end cap which can and does leak from the rubber gasket.

Like Rob said, your problem may well be more involved as you had or are having issues with the alternator. Is something pulling a lot of electrical current somewhere etc?

Check the relay first and report back.

[tdsull]

I replaced the relay in Feb and had good success. But last week my tach. went haywire again and alternator wasn't charging. The volt meter on the chart plotter never read more than the current battery state. For the last couple months it was consistently reading 13.9 underway. I can't seem to find a loose connection so I am swapping out other items that are on the same circuit. I scanned in and traced the wiring diagram from the manual and it looks like the SW switch is connected along the same path, does anyone know what the part number?? It looks like #18 in the diagram, but I would like confirmation before ordering. I replaced the thermostat today as well.