Yanmar 3JH4E starting issues - Sun Oddysey 39DS

[SeluneSailing]

We have an intermittent issue on our boat where the engine won't start.

Usually, in the morning the engine starts first time, no problem. However the issue arises after we have had the engine on for a while and then turn it off and then try to turn it back on. If we give it a few hours to "cool off" the engine will regain it's sense of humor and turn on again, not good. When we turn the key either we are greeted by silence or one singular click.

Not entirely sure what the issue could be. What confuses me is why it will turn on in the mornings, this makes it tricky to demonstrate the issue.

 

[kloudie1]

Welcome to the forum! Much good information here in the General Downloads section.
Your problem is most likely a bad electrical connection that could be anywhere between the battery and the starter motor. On Yanmar, it is usually in the voltage supply to the starter solenoid, but without trouble shooting it is a shot in the dark. Time to get a voltmeter and start checking connections when under electrical load, not just when turned on.

 

[jssailem]

Your description could be associated with a questionable electrical connection in the starter system.
When the engine is cold, the metals allow the circuit to provide the needed electrical power to start. When you warm up the engine, the loose connection is heated (expanded), creating an open circuit condition.

You get a low battery voltage type symptom: "When we turn the key, either we are greeted by silence or one singular click."

All this is the best SWAG. Loose connections are one of the usual suspects for what you describe.

Checking the connections is an easy task to accomplish. Be sure to disconnect the battery before working with metal tools near electrical connections.