1980 Tower of Power Troubleshooting

[houstonmat]

Hi all,

I finally have a weekend free to do some troubleshooting on my 1980 inline 6 Merc 115 and I'm hoping to get some opinions.

A couple of weeks ago I started the day on a battery fresh off the charger. The motor started but I could tell the battery wasn't strong - I figured running the engine would keep it charged enough to make it through the day. Started and stopped a few places, then made a ~15 mile run near top speed. About halfway back, the motor died at full speed. The battery was too dead to get it restarted. When I got home, I put in a known good battery and it started right up and idled fine. Unfortunately I didn't have tools available to troubleshoot.

My question is this: Does that sound like a stator issue or rectifier...or both? Do you have any troubleshooting tips or links to specific procedures? I'm planning on firing it up on the good battery, checking running voltage and pulling the battery to see if the motor can run while disconnected. Any other advice?

Thanks in advance.

[daytrader]

Id think twice about disconnecting the battery while running, I dont think its good for the electronics.

[Dave Strong]

Could be stator or rectifier issue, shop manual, ohm meter, and DVA will be needed to narrow it down. Battery connections clean and more than finger tight?

Dave

[pt-73]

Hi all,

I finally have a weekend free to do some troubleshooting on my 1980 inline 6 Merc 115 and I'm hoping to get some opinions.

A couple of weeks ago I started the day on a battery fresh off the charger. The motor started but I could tell the battery wasn't strong - I figured running the engine would keep it charged enough to make it through the day. Started and stopped a few places, then made a ~15 mile run near top speed. About halfway back, the motor died at full speed. The battery was too dead to get it restarted. When I got home, I put in a known good battery and it started right up and idled fine. Unfortunately I didn't have tools available to troubleshoot.

My question is this: Does that sound like a stator issue or rectifier...or both? Do you have any troubleshooting tips or links to specific procedures? I'm planning on firing it up on the good battery, checking running voltage and pulling the battery to see if the motor can run while disconnected. Any other advice?

Thanks in advance.

Sounds to me like you should start with a good battery. Fresh of the charger and not strong is not a good start.
If the charger can't bring the battery up you can't expect these old charging systems to do it.

[rock]

I would have to agree with the above post.

Rock

[outasite]

Disconnecting the battery while running,will instantly blow the rectifier! If the battery is in fact good,Put a test meter set on 20volts across battery while running above 2000 RPMs Should read more than 13volts.Think the rectifier is most likely dead.

[A164]

If it is an old carburated ingine.
Then when the engine is started, it is able to run without any power on the Battery. Then the Battery is only used to start the engine.
So it could be your stator that is burned.
Note: that a lot of other components can have faults also.
regards Thomas