charging problems 898 merc

[dbdupont]

I have a 1983 silverline with a 898 merc i/o. While out fishing I noticed the volt gauge was reading 12 volts with freshly charged batteries, with in a hour the engine started to miss and the batteries were dead. I replaced the alternator with a new mando style 3 wire 55 amp unit. Upon starting the engine ( with fresh batteries) my volt gauge was still reading 12 volts. I am able to start the engine and disconnect the batteries while the motor is running but am not convinced that I have the problem solved. Does anyone have any ideas for me on what to check to fix my charging issues.

 

[Silvertip]

Re: charging problems 898 merc

Well sir -- by disconnecting the batteries with the engine running you may have toasted another alternator. Don't do that! Use a known good voltmeter to check voltage at the battery with the engine running at about 1500 RPM. If the charging system is working it should read in the 13.5 - 14.5 volt range. A battery will typically measure 12.6 volts with the engine off and fully charged. It may be your instrument panel gauge is not accurate.

 

[dbdupont]

Re: charging problems 898 merc

Will keep my fingers crossed that I didn't ruin the alt. Is it possible that I have an open circuit somewhere and that is putting a load on the alt. If so what would put enough of a drain that would effect the charging system?

 

[dbdupont]

Re: charging problems 898 merc

Well all charging problems solved. The guy i bought the boat from was a electrical idiot and he sure loved red wire!!!!!! Any way I have the ignition wire and the volt gauge wire backwards. Switched them around and 13.5 volts at the gauge.