Yanmar 3JH5E Won't Start

[fthurlow]

I have 2 Yanmar 3JH5E engines on my 2010 Lagoon 400, each with about 2500 hours, and the starboard engine won't start and won't even turn over.

Here is the chain of events -
* Boat was on hard for 5 months having sail drives replaced and multiple other projects. During this time the engines were only started briefly to insure sail drive operation (water hose provided water for engine)

* On day of launch the stbd engine wouldn't start and had low voltage warning on stbd battery. I ran the generator to charge the battery and it started after about 15 minutes. Mechanic advised me to replace the battery which was about 5yrs old

* About 3 hours into the trip back to home port the tachometer and gauges went to zero but engine was running fine. I suspected low battery voltage was cause but why wouldn't alternator be keeping battery charged unless battery was toast

* Arrived at dock and after tying up I tried to stop stbd engine but switch didn't work and had to turn off fuel to stop engine.

* I removed the stbd battery and replaced it with the generator battery and was able to start engine but still couldn't stop it via switch and had to cut off fuel again

* Replaced the stbd battery the following day with new battery and charged up overnight to 13.1 V

* Attempted to start engine but doesn't turn over. I get the tone and the 3 lights but when I try to engage the starter - nothing.

* Could the kill switch be the cause of this? How can I check this or override it to confirm?

* I prob need to check the starter circuit and also the alternator to ensure it is working properly. Should I need to re-prime the fuel filter as there may be air in the line? Is there some cutoff that disengages the starter if fuel is not present?

* What else do you recommend I check?

Thanks in advance for your help & comments.

[kcj]

Does yours have a starter relay??? I Have a 2003 3jh3 with a starter relay to excite the starter...real easy to jostle those relay wires...especially if working around the starter connections...also check the battery ground connection on the motor...

Good luck..

[fthurlow]

Thanks!

[S/V Illusion]

Originally Posted by fthurlow

Here is the chain of events -
* Boat was on hard for 5 months having sail drives replaced and multiple other projects. ).

Since we’re guessing, my guess is this -“multiple other projects”.

[jkishel]

Failure to turn over has nothing to do with the fuel system or kill switch itself. Failure to turn over and poor charging is often caused by bad battery cable connections, especially the negative connection to the engine block as kcj indicated. Clean and tighten all battery cable connections and report back.

[wingssail]

Originally Posted by jkishel

Failure to turn over has nothing to do with the fuel system or kill switch itself. Failure to turn over and poor charging is often caused by bad battery cable connections, especially the negative connection to the engine block as kcj indicated. Clean and tighten all battery cable connections and report back.

I strongly support this conclusion. The fact the the tach and kill switch failed means that no or insufficient voltage/current are getting to the panel. When you put new batteries it increased the voltage but the basic problem exists and is getting worse. It is a cable/connection problem between the battery and that engine.

[skipperpete]

To remove the sail drives the engine is usually released from the engine bed and moved forward to separate the spline on the Saildrive so it’s reasonable to expect that the earth cable and the harness sockets ( cunningly placed below the mixer elbow and manifold drain) have been disturbed so maybe pop open the harness plugs and see if there’s any corrosion or looseness there. The main engine ground is often found on the same bolt as the harness ground so perhaps give that a cleanup too.

[Granfalloon]

A mechanic in our marina always said - Check the Negative GROUND 1st - clean it reattach and check.