motor died while running at half throttle

[slow but steady]

Hello to everyone out there in boating land. I have been reading these threads for some time now and have found many answers to questions I've had. This is my first time asking for help but I cant seem to find the information that I now need. I have a 1982 Evinrude 50 hp outboard (e50belcnr). I bought it about a year ago with a 14ft Mckee. It ran OK but didn't have much power but a fuel pump rebuild solved that. Not long after that I lost a ground and traced it out to the the large red connector on the port side of the engine. It had broken right at the pin terminal inside the connector. After that I got to looking at the other wires and connections, and several of them didn't look so good, so, wanting a dependable motor I replaced all terminals and connection with new terminals w/ heat shrink. Also replaced all wires that looked questionable and wrapped them in anti-chafe conduit. Other work that has been done recently for different reasons are, both carbs have been rebuilt, both coils ,power pack, spark plugs, thermostat, water pump, head gasket have been replaced. Some were bad some were for precaution. Well that's pretty much the history. My question is, will this engine run if the battery goes dead. I ask that because yesterday while going along about half throttle, the engine made a loud noise (like a broke rod) and cut off. After finding that I could turn the flywheel all around and no internal noise I tried to start it and the battery was dead. Got it towed home, charged the battery and checked the rectifier and stater with the ohms meter. They both checked good. Started the engine and battery was charging. Did the wiggle test to check for bad connections. None found. So anyway, would a weak battery cause the engine to cut off?
Sorry for the long novel but I wanted to give as much information as I could.
Thanks in advance,
Joe

 

[Barnacle_Bill]

Re: motor died while running at half throttle

No, the battery is only needed to start the motor and operate accessories. However you shouldn't disconnect the battery while running as you can damage the rectifier/regulator.

 

[jonesg]

Re: motor died while running at half throttle

Something let go, the battery issue "might" be unrelated.


If you can , try a dentist mirror to peek under the flywheel, look for displaced magnets.

Does it run good now?

 

[slow but steady]

Re: motor died while running at half throttle

That's a good idea. I'll check that. It could very well be unrelated. Sometimes things like that can sure get you off track.
At any rate, yes it's running just fine now but I don't feel comfortable at all taking it out until I can come up with something. I'll check out under the flywheel and post what I find in a hour or two. (as soon as it gets light outside)
Thank You Very much,
Joe

 

[slow but steady]

Re: motor died while running at half throttle

OK, just pulled flywheel and inspected. No problem found. All looks good.
Any other ideas? I was hoping that was it.
I was wondering, would the power pack cause the engine to stop or cause a misfire if the voltage was low or if there was a voltage spike due to weak battery? That would explain the noise if the wrong cylinder fired at that rpm, kinda like a crossed plug wire type effect. May be way off, just wondering.
I know on a car with module and coil pack low voltage or a spike will do all kinds of crazy things.
Thanks,
joe

 

[jtexas]

Re: motor died while running at half throttle

When you say "tried to start it and the battery was dead," are you reporting a symptom: "the starter motor did not engage when I turned the key," or a cause: "I measured battery voltage and it was below 12 volts"?

In my experience, the wiggle test is ok for preliminary troubleshooting -- a positive result means you do have a bad connection, but a negative result does not always rule it out. Corrosion not readily visible can be lingering there on the battery post, causing intermittent problems before the connection fails completely. If you haven't already, I'd recommend remove, clean and retighten those connections.

There are types of ignitions that require battery voltage to generate spark, yours is not one of them. The car has a problem with low voltage because of all those fancy schmancy sensors and computers, which your motor has none of. Your outboard will run perfectly without a battery (although as mentioned above, doing so will burn out the rectifier).

Not being an electrical engineer I can't state with final authority that it's impossible but I'm pretty sure it is. The connection between battery and ignition system is through the charging circuit (and obviously, engine block common ground).

Have you done a compression test?

You said, "..the engine made a loud noise (like a broke rod) and cut off. " Maybe something broke in the gearcase?

 

[slow but steady]

Re: motor died while running at half throttle

OK. Thanks for the answers to my question. I'll keep looking for a explanation of what happened. For now, everything is working and running just fine. I may take it out tomorrow with a friend in another boat following and see how it does.
Intermittent problems, what would we do without them.:redface:

 

[Fed]

Re: motor died while running at half throttle

Could you have hit something with your prop, check it for dings.

 

[slow but steady]

Re: motor died while running at half throttle

It's possible we could have hit something. My oldest son was with me and he told me that's what he thought happened (that we hit something).
I checked the prop but didn't find any dings or chips on it. Its a brand new prop by the way. A 4 blade. That was the first time we had it out, the day it cut off. Ill pull the prop off tomorrow to see if maybe the bushing slipped or something.
Anyway, thanks for the suggestion,
Joe