Starting trouble - Yanmar

[Sea Mistress]

We have a Yanmar 75 HP 4Jh3-TE that won't start after running for three to four hours straight. The first time it happened we did a five hour transit under power came alongside a dock then when to shift and restart but diesel wouldn't start. The power came on but when I pushed the start button you could see a current draw on the engine electrical meter but nothing happened. We started the generator to charge batteries but no change. Checked wiring etc but all seemed well. Rigged the dinghy and got it to move us to other berth. When we arrived tried the diesel and it started right up.

Yesterday we did a four hour transit. Stopped to fish and stopped diesel. Once again wouldn't start same indications. Tried manually running strarter with screw driver and motor spun but selenoid didn't kick forward and engage so no start. I think this was me not getting the screw driver the right spot. Once again after 2 hrs of waiting diesel started fine.

I am trying to think what would cause this. Any thoughts?

 

[Stu Jackson]

"Checked the wiring" --- in most cases of the situation you describe, the culprit is the main ground wire on the engine. Suggest you check the ground lug, the wire into it and the cleanliness of the connection. While it may "look good" you NEED to remove it, pull on it and generally redo it if it is in any way suspect. Happens to our guys all the time and we've made it an item in our Critical Upgrade topic. http://c34.org/bbs/index.php/topic,5078.msg37179.html#msg37179

Good luck.

 

[Eddie7045]

Sounds like you have break in the windings in the

starter that is accentuated by heat from the engine.

 

[Steve Dion]

This problem has been solved by adding a relay between the starter button/key or replacing the wire. Most of the time the wire had high resistance from corrosion. You may want to try a temporary fix with a new wire to see if it does the job.

 

[Bill Roosa]

You can also just replace the factory quick connects (about 11 of them) with plain splices and get the the same result (costs less too). Seems that the yanmar starter solenoid has issues with low voltage/current resulting in no starter when the control wire can't provide the proper current due to lots of little losses in those 11 connections between the ignition switch and the engine ground.

 

[tomgrigsby]

You could lift the small hot wire off the solenoid and verify you're getting 12 volts to it when you push the starter button. Check all connections for frayed and broken wires of course - if you have a frayed connection with only a few strands still connected, you'll get voltage but there won't be enough current to activate the solenoid or motor. The screwdriver thing is the tip off I think. Starter is failing and needs to be replaced. Solenoid should have kicked out when you put the screwdriver to it. It has internal wiring insulation that is breaking down when it is hot. I'd say replace it. If on the off chance it doesn't fix it, it never hurts to have a spare starter, but I'm pretty sure that's your problem.

 

[Sea Mistress]

Thanks I did find a little corrosion on the grounding wire and cleaned it up rest seemed fine

 

[Sea Mistress]

Solenoid voltage

After a series of these challenges the diesel finally failed to start at the fuel dock and an electrician was available to troubleshoot. There was a drop in voltage to the starter Solenoid when the wiring was hot(warmed by extended operation). We have installed a solenoid to operate the solenoid and the problem has been solved.