Need Yanmar 4JH3E Help Urgently

[hlev00]

I've been in this situation. A stuck relay is usually the problem but you may be in more of a hurry than a lot of lead chasing. I've done the screwdriver technique. It is a little exciting but easy to do. Small spark then the engine should crank.

The first part of this youtube explains what you need to short to jump start with a screwdriver. This isn't the same engine but the starter I believe is nearly identical. Pull back the covers, use a screwdriver and you are probably good to go.

Check that ground stud too.

https://www.youtube.com/watch?v=Mp2cGDa1VOU

Or you may be under tow already.

[SV Sedna]

I had starter problems this summer. I was convinced it was the solenoid. It was not. Determined only after playing the remove and replace game. These have a magnetic relay (solenoid for the solenoid) bolted to the block just forward of the starter. It helps eliminate problems with voltage drop if you have a long run of wires to the control panel. In the wiring diagram it is an optional part. I removed it and placed the ignition wire directly on the solenoid that went to this relay first. I will replace it with this next spring. The part number changes a couple times and this was the original one installed on my engine. Lots of research and luck to pin it down exactly.

https://www.ebay.com/itm/Yanmar-1291...53.m1438.l2649

PM me if you want a copy of the full parts number guide for our 4JH3 series.

[arthur.watson.1]

Check the ground strap from the start battery to the engine. Corrosion there caused my 4JH43 to play dead. I disconnected the strap, cleaned up the ring connector (with my Swiss Army knife); bang.

[Tom_F]

Thanks to all of you. I’m making a list and will run through it until it starts or I get fed up and turn it over to a pro.

[adjo]

Originally Posted by boatbod

Yanmar 4JH3 typically have their harness connectors located right underneath the exhaust elbow. Any leaks causes the rear engine mount to corrode and the harness connectors to become intermittent. Check there first. After that look for a small square solenoid attached to the engine wiring harness somewhere relatively close to the starter motor.

As Boatbod mentions any leaks from the exhaust can dip onto the electrics and starter motor. I've tried to stop the leaks but still get an occasional small drip at the exhaust manifold so have fitted a deflector to protect the vulnerable parts.

[Tom_F]

So, she finally started. Finding a cold starting cable and tapping on the solenoid seem to have been the keys, coupled with using a portable jump starting battery pack (even though the battery was OK at 12.8 volts I think the cold was really impacting starting). All the electrical connections were solid with slight surface oxidation on the metal but no real corrosion to worry about and no leaks in the exhaust system.

Thanks again for your help and insight. As always you guys came through with the advice I needed.