1987 90 hp merc, not charging battery yet will run when i disconnect battery. Stator?

[Jeffreymiller]

90 hp merc, new to me. Cranks and runs with battery connected yet not showing charge on multimeter. Disconnect the battery and motor continues to run. Shows that stator is working to keep spark to motor yet no charge. Replaced Rectifier and Power Pack. Need help quick.

 

[Barnacle_Bill]

Re: 1987 90 hp merc, not charging battery yet will run when i disconnect battery. Sta

Test the charge coils on your stator. Never run the motor without a battery being connected. You may have damaged your new rectifier.

 

[j_martin]

Re: 1987 90 hp merc, not charging battery yet will run when i disconnect battery. Sta

Yep, if you put in a stock Murkery rectifier, you toasted it. It probably took out your alarm electronics also.(oil alert)

Never, no never run a Merc outboard without the battery, even if it's a bad/dead one. The battery is the last leg of voltage regulation that prevents damage elsewhere.

Disconnect the yellow wires from the stator. Connect an AC voltmeter across the wires and start the engine. You should get about 10-15 Volts per 1000 rpm AC across those wires.

With the engine off, measure the resistance between those two wires. It should be less than one ohm, but not 0. (hard to measure with a cheap meter) There should be no continuity between either one and ground.

If that's good, then your regulator or rectifier is bad. When you replace it, be sure you have a good battery connected well when you start the engine.

hope it helps
John