Mainship Pilot 30 not starting

our fairly new to us 2003 pilot 30ii with 315 Yanmar was left off the charger for a night with some 12v stuff on (refrigerator) and would not start the next day. I recharged the batteries and still no go. Not knowing the age or condition of the used batteries I installed two brand new 800 CCA Batteries. All I get is some chattering at the helm start button (like a relay ?) as well as a few clicks at the starter but never engaging the engine. I have looked at and tried to make sure all wires at the helm switches are well connected and have checked the smaller wires at the starter. Still the same condition. I am not too versed on electrical and not sure I want to venture any further but before I make the call to the marina I would appreciate any insight from anyone with similar issues on this engine. Thanks!

Have you checked the condition of the battery cables? Loose or corroded connectors on the battery cables maybe.

What Dave said.

On the solenoid, the battery cable connects to one of the large posts, the other large post connects to the starter. The small post with the tab is the circuit that energizes the solenoid that makes the starter rotate and engage the engine.

Touch a wire, piece of metal, or screwdriver between the solenoid post where the battery cable connects and the small post with a single wire. The small post sometimes has an "S" for start. It causes the solenoid to engage the starter. That bypasses all the wiring to and from the control console.
If the starter works then the battery cable and batteries are ok and the problem is between the tab and the control console. If the solenoid clicks or the starter hums, then you need to replace the starter. Most auto parts stores will check the starter for free.
If you want to check out the solenoid further, touch a screwdriver across the 2 large posts. There will be sparks. If the starter turns, and it didn't before, then it's the solenoid.

Do all your house lights work properly? If they are dim or there is other indication of power shortage go back below and look for an odd battery cable you may have missed in connecting the new batteries.

pete

Like Lepke says, just be aware that there will be a big spark, the starter will engage and it will be loud, the engine will probably start.

All this is good, just don’t be startled and put your self at risk. Things will be spinning and very loud.

Chattering like you described is a symptom of poor connection/low voltage. Look for loose connections and/or corrosion.

I have the same boat & engine. The first thing I would check is the joint where the negative battery cable connects to the engine block, then all the other main power cable connections. A good cleaning(wire brush, emory cloth) and treatment with Corrosion X (not WD40) is a good investment.

Be very careful trying to by-pass the starting circuit with a screw driver or other metallic object. A "hesitating" start can result in damage to any number of expensive goodies - solenoid, starter, fuel solenoid valve - just to name three. Also, high currents can weld your screw driver to the post, spinning the starter till it runs the battery down. An in tight quarters you can get burned - just be careful.



The starting circuit is shown in the engine manual and is pretty straight forward. You should be able to check it with an ohm meter and look for corrosion .


And here's a tip. The helm swing out is nice but still awkward. You can take the screws out of the lower switch panel and let it tilt out the front, making access to wirng terminal very easy.