8.1 Volvo Alternator??

[ACV97]

The volt meter on our 8.1GI would not go over 13V, and the boat ran bad (3600RPM max). I changed the plugs and now the boat runs great and the alternator is charging 14V. Actually 14.4 on DVM. Why would bad plugs decrease the volts when the RPM is the same. 2000 RPM should be the same volts I would think.

 

[drrm123]

Re: 8.1 Volvo Alternator??

no the plugs did not make a difference. it's depends on the current voltage of the battery how much output the alternator will produce, easiest way to explain is if on your car you first start it and heavy load to crank engine will drain battery and charging system will put out more to recover, so after battery has close to a full charge system will taper off a bit. turning on headlights will be additional drain on system and alternator output will increase, i believe system has to put out a minimun of 13.7 volts to maintain 12 volt system.

 

[abj87]

Re: 8.1 Volvo Alternator??

your golden with 14.4 volts at the alternator. who knows why it was 13 with the bad plugs. Check your gage connections any reistance in them will chage the voltage.

 

[Don S]

Re: 8.1 Volvo Alternator??

I changed the plugs and now the boat runs great and the alternator is charging 14V.

The plugs won't cause it, but you do have a problem. Something is loose or corroded and in the process of changing the plugs you moved it. Check everything in the area. Including alternator connections, starter connections, and anyother connection you even came close to.
It didn't heal. Mechanical things don't heal, they do however "Lay in Wait" for the unsupecting, and spring on you at the most inopertune moments. I think Murhpy is his name.

 

[ACV97]

Re: 8.1 Volvo Alternator??

That is why I asked it puzzled the crap ou tof me. I did not know with the EI if there would be something like a dead short causing extra drain on the alt making the volts low. I will double check anything I might have hit or loosened up during the process. It is a stumper though, everyone I have asked have about the same look on their face.