Help! Outboard shut off

[George1702]

i just bought a 1993 Stratos 274 FS with 1993 120HP Johnson outboard. I floated it for the first time today. It ran great but at one point I was running at full throttle, and started to ease back on the throttle. The engine immediately died with a slight clunk. I put it back in neutral, turned the key and nothing. No click, no crank, nothing. Battery was fully charged battery cables are sound.. I got towed back to the dock. I tried the key several times. Nothing. I got her back on the trailer. Here's the weird part. I stopped by a local hangout. Several friends came out to see my boat. Several times I tried the key and nothing. Then after about an hour, I was showing another friend the boat, turned the key, and the starter groaned a bit. Like trying to start on a dead battery. I tried it again a couple minutes later, and it fired right up. I immediately shut it off.
What could cause this? something overheated then cooled? Intermittent switch? I'm fairly experienced working on boats, and have an electrical degree. What could cause an engine at speed to suddenly die, then not even clink/crank, then after an hour or two, slowly start to crank, then fire right up?

 

[GA_Boater]

Welcome aboard.

It sounds like it overheated and seized from thermal expansion. As it cooled, the parts gradually increased clearances, the starter groan, and finally enough to crank and start.

No alarms? Have you replaced the impeller?

 

[racerone]

Running with VRO in service ?----Or running with 50:1 premix or just not sure ??----Gear oil checked ?----Overheat horn tested ?

 

[George1702]

I suppose an overheat is possible but why would the starter not even click. If the motor seized even temporarily, the starter should have at least tried to engage. I didn't change the impeller yet. It is moving water, but not a very strong stream, so I will be changing it. The alarm works but never went off during this event. I'm using a oil tank & VRO. Based on running on earmuffs, it seems to be oiling ok. I checked the gear oil, it looks brand new and full. I'm still thinking electrical, but you have both given me some things to consider.

 

[racerone]

Post #1 says that the starter---" groaned a little bit "----And -----" slowly start to crank "-----Stopped with a " clunk " -------So could you explain again what happened.----I am working on a 1991 65 HP Evinrude now that stopped with a " clunk "------#2 piston came apart.------Put a hole in the block.---Sheared the flywheel key when it came to a " dynamic halt " so to speak.

 

[George1702]

I was running at full throttle and everything seemed fine, I started to throttle back and the engine quickly lost rpm (faster than the throttle movement) and stopped. The end of which was abrupt. It didn't slam hard, but it didn't wind down normally either.
Again the odd thing is when I turned the key nothing happened. No click from the solenoid or any sound of the starter activating. For the next couple of hours, I tried the key and again, nothing. No click no sound. Then I tried it and got a slight groan ( like a motor trying to start on a dead battery). 20 seconds later, tried again and the engine fired right up like nothing had happened. I'm beginning to think the other guys that posted maybe right. It wasn't moving very much water through the impeller, and that water was pretty hot. I have a water pump rebuild kit on order and won't run it until that is changed. But I'm still confused as to why the starter wouldn't at least try to engage. Dumb question, but has anyone encountered a main fuse that "overheated" enough to prevent start, but didn't fully blow?

 

[oldboat1]

Check and clean battery connections until shiny. Overheating ignition parts can temporarily stop the motor. If you have a water-cooled regulator/rectifier on your model, overheating can be a good deal more dramatic.