Electrical Gremlin or Solenoid?

[rigormortis]

Folks:
Need help with this one. GordM has tried to help but I am too dense. Have Yanmar 4 banger, 4 house batteries (total 820 amp), new starter battery, new battery switch, new ignition switch. This is what happens: I can't start the engine (no turnover) if I don't switch off all battery draw for about 10 minutes before trying to turn engine over.
The battery draw is usually just fridge (6 amp while running) and maybe light or two.
I am thinking my system voltage needs to recover (?) it's breath for a few minutes in order to supply enough juice to the starter.
Or, maybe I have a sticking solenoid which needs a couple of impulses to get it going. However, I have found that giving the system a rest (?) for 10 minutes usually does the trick. WTH?
I am in Cook Islands and have had this problem ever since I left Portland, Oregon last year.
Makes me nervous thinking about emergency (right now) engine starts.
Any help appreciated.
Pete

[btrayfors]

There are several possibilities, but I'm betting that you have a bad connection somewhere, probably a bad ground. CHECK ALL YOUR BATTERY CABLE CONNECTIONS CAREFULLY to be sure they're clean and tight. Checking means removing and cleaning, then replacing with proper torque.

A start battery should not need to "recover"; it should start your engine instantly. If it does not, then suspect the cable connections first, the battery capacity second (expecially if you can start the engine easily using the house batteries).

If it's not connections or battery capacity, it could be a faulty battery switch (I recently ran across one on a client's boat which was really bad, causing a serious drop in voltage). It could be a faulty solenoid or, possibly, a faulty starter. Could even be an intermittent in the wiring harness to the engine, or a badly corroded or otherwise deficient starting switch.

Try the easy things first. That's usually the path to finding the fault fast.

Good luck.

Let us know what you discover.

Bill

[daddle]

"It's almost always a bad connection."

That's what I'd guess from here. It takes about 3 dozen connections to turn a starter. One of them is loose.

It may be more "the second time" than "switching off all other stuff".

Voltmeter on solenoid's small wire (the start button wire) should give a clue.

I discovered an interesting quirk here: The preheat button 'locks out' the start button. Maybe this is common. But I'd never noticed until one day when I was in a 'panic' and held both in to save time. More panic ensued until I let go of the Preheat button.

[senormechanico]

Previous boat had a bad connection (as have lots of others) in the Yanmar multi connector which on the 3HM35F was located at the rear of the engine. The fix was to unplug, spread the split pins, shoot some contact cleaner in the socket and reconnect it. That fixed it until I sold the boat.