Yanmar Starting Issues - Runs in Off Position

[Eds-Therapy]

I started my Yanmar (3JH4E) after winter storage and it cranks over, but will not stay running. The key was in the "ON" position, and oil pressure alarm works. After several attempts, I found that if I start the engine and quickly switch it to the "OFF" position, the engine will run as normal, however none of the gauges work. The engine/transmission function as usual. To stop it, I turn the engine to "RUN"
I had this issue last year after storage, and suspected the ignition switch, before I went to replace it, the problem went away. All the connections appear in good shape. Has anyone seen this before?

 

[Sailboat.Sequoyah]

You kill that engine with the ignition switch, not with a fuel stop?

 

[Eds-Therapy]

The engine will not continue to run in the "ON" position. To stop the engine, I turn the key from "OFF" to "ON". To start the engine, I turn the key to "Start", let it crank, then quickly move it the "OFF" position and the engine keeps running. Weird thing is that the engine did the same thing last year after storage, then the problem went away. I never had an issue the rest of the season.

 

[Davidasailor26]

My guess is that the On position has gotten shorted with the fuel cutoff. Turning the key off isn't really designed to stop the engine, so I'm not surprised that it keeps running that way. The gauges will stop because the electric is cut.

Once you sort it out you might want to check your alternator output. It's not really designed to have the key switched off while the engine is running, so hopefully you haven't done any damage there.

 

[Don S/V ILLusion]

Do you have an electric fuel shut-off?

 

[Eds-Therapy]

I do not believe so

 

[LeslieTroyer]

Do you have a lift pump that runs with key off ? And somehow the OP switch is killing it??

 

[Davidasailor26]

I do not believe so

How do you stop the engine when the key is working normally? The service manual says that to stop the engine a push button on the instrument panel should be pressed. That usually suggests an electric cutoff, and my suspicion is that that wire is shorting to the On position wire. Do you have such a button, or some kind of cutoff lever?

 

[Davidasailor26]

So, looking more at one of the wiring diagrams in the service manual, I suspect that the matter might just be that the stop button itself (if equipped) is stuck closed.

Item 11 is the key, and the other part of the diagram says that turning the key "on" connects post 30 to post AC. Once those are connected the fuel cutoff switch (item 12) will be enabled. Switch in any other position takes the gauges, lights, and cutoff switch out of the circuit. So since you say the engine stops as soon as the switch goes On, that cutoff switch is probably just sitting stuck closed. It may have been that way at the start of last season too, until it warmed up enough to evaporates some moisture, or the contacts freed up somehow.

 

[Eds-Therapy]

That is a great point! Under normal operation, when the "ON" is selected.. I hold the "STOP" button, and it shuts off. It is very possible that there is moisture in the switch and needs to dry out somewhat. I am curious if I temporary disconnect the stop switch if solves the issue. That would at least start ruling things out. Thank you!

 

[NYSail]

Start by physically looking at the real of the panel...... separate wires and make sure things are tight. Sounds like a crossed wire. Some times you can see and solve an issue.

Greg

 

[Benny17441]

It seems like you have an electric fuel shutoff solenoid to turn the engine off. It seems to me that the solenoid may be grounded or shorted. It could be the solenoid, it could be the Key Switch (diesel engines do not have ignition ) or it could be the wiring.

 

[NYSail]

It’s an electric fuel shut off........ get a new key thingy....... bet that fixes it. It’s a simple issue. And yes I always heard never turn the key to off or you will damage alternator..... but that was with older yanmar engines. I have same panel for my 4JH4E.
Good luck and looking foreword to hearing the solution.

Greg

 

[Gunni]

These electric fuel cut-off gizmos rank right up there with digital engine control systems on sailboats - what do you do when the fancy tech quit’s working? It appears that the electric engine stop fails in the “will not run mode”. Which seems even less useful than “will not stop” mode, since I can always find a way to get to neutral and cut off the fuel supply. Anyone know what the guidance is for these yanmar engine controls with electric engine stop? Like maybe something short of pulling the panel loose and twisting wires together. Imagine having to do that on a rolling deck.

 

[Eds-Therapy]

Just an update to the issue. I went down on Sunday, and started it up. The engine operated in the "ON" position and acted normal. I did not touch any of the wires as I was planning on doing that Sunday. Everything behaved as normal. I tested it several times. This was the case last year as well. First day out of storage, it gave issues. Days later, it resolved itself.

 

[Sailm8]

I hate those self-healing episodes.

 

[Sailboat.Sequoyah]

Condensation shorting components, drying out when the boat is opened to the air?

 

[Jake N Eggs]

If you have an engine fire suppression system it could be wired through a relay to shut the engine down. Maybe the pressure switch on the extinguisher bottle is opening in the cold and the hysteresis of the switch keeps it open until it warms up. (pressure in the extinguisher on the edge of being too low) There is a bypass switch on mine which will allow the engine to run.

 

[All U Get]

Tell your wife that the only way to know for sure is travel to the islands next winter and don't ignore the boat.

 

[senang]

What Jake N Eggs says. It must be the low pressure in the automatic fire extinguisher. The weather was warmer and there was more pressure in the extinguisher. Try the override switch on your panel next time.