yanmar 4JH2E with type c instrument panel

[KTHenderson]

We own a Vector 39 with a Yanmar 4JH2E with a Type C instrument panel.
The engine has under 600 hrs.
Recently we have not been able to start here with the key. It started fine 3 weeks ago.
Light comes on so there is power to the panel
Batteries are like new.
Could it be a fuse?
Any suggestions before I call a mechanic

Thanks

[jkishel]

Check that the batteries are well charged. If so, start with the battery cable connections. First check the negative (black) cable connection to the engine block. Turn the battery switch to off and remove the bolt at the block. Clean the terminal(s) with sandpaper and reinstall. This addresses the vast majority of non-starts. If the engine still won’t turn over, clean the rest of the battery terminals being careful not to cross positive and negative cables. Also clean the connection at the starter motor. If the engine still won’t turn over report back and we can address next steps.

[Ericson38]

Originally Posted by KTHenderson

We own a Vector 39 with a Yanmar 4JH2E with a Type C instrument panel.
The engine has under 600 hrs.
Recently we have not been able to start here with the key. It started fine 3 weeks ago.
Light comes on so there is power to the panel
Batteries are like new.
Could it be a fuse?
Any suggestions before I call a mechanic

Thanks

Disconnect and clean wire harness between panel's wire loom and engine (connection plug close to starter).

[kcj]

Got power at the starter??? My recent starting issues all related to starter relay failure, or related wiring. or the negative connection on motor...went from no problem to no start in an instant...

[bstreep]

As others have pointed out, the wiring is suspect. Yanmar used the minimum gauge wire they could get away with. With time and corrosion, the effective gauge of the wire shrinks, to the point it just doesn't work. Check all of your connections, including the plugs, clean them up. Then go the replacement route. This is very, very common.

[Captain Bill]

I believe these engines have a separate starter relay on the lower left side of the engine just like my 3jh3s. I have had numerous problems with corrosion on the terminals of this relay. Usually they are easy to clean up with little sand paper.