Voltage

[Esox_Magnum]

My volt gauge was reading low while on vacation so I switched over to the volt reading on my HDS and with WOT both only showed about 11 volts, shouldnt it be near 13? May explaine my motor randomly loosing rpm at WOT when in rougher water or going over boat wakes? Motor has had this issue of loosing rpm since being rebuilt this spring, mechanic is at a loss as to whats wrong and so am I...

[aanderud]

It should actually read above 13 volts at WOT. Can't say how that would explain the loss of power when going over waves though.

[delcecchi]

One or more loose connections from when it was put together. Alternator not putting out much/any current, and ignition gets interrupted when connection is jostled.

That is my guess.

[eurolarva]

What motor is it and what year? Most older outboards are not dependent on alternator output voltage. Once they start the battery voltage is not needed to keep it running. I would think a coil is going bad. A lot of times they will run fine till they heat up then can give intermittent problems. What sucks is it is tough to troubleshoot at a marina.

It also sounds like your voltage regulator could be bad or your alternator. Normally a voltage regulator would give you high voltage over 14 volts when bad.

[boatfixer]

98 75 mercury I believe is what he has.

There is no alternator. There is a stator which produces current for charging and the energy for the ignition system. There are tests for both. Personally I would start with the stator once I verified all connections are clean and tight. Your mechanic should have a DVA meter and the test procedures.

[delmuts]

I think he has a 115, but not certain what year.

[Esox_Magnum]

Sorry Merc 115 1991 vintage...checked all connections myself as well as rechecked my the mechanic..... puzzeling problem to say the least....

[boatfixer]

That one falls right into the time frame when they had stator issues.

[marine_man]

Do you have a tachomoter on your boat? Is it still reading correctly?

marine_man

[eurolarva]

Seems to me the black ones were the bad stators and the red ones were the replacements. Been awhile so it could be the reverse. Check out the color of the stator under the flywheel and post it. I know another forum and I can verify the one that was the bad one

[boatfixer]

Other forums, pffft!

Black are the bad ones, reds are the good ones

[Esox_Magnum]

I'll have to look, tach hasnt worked right since I owned the boat, had a mind of it's own for the first year I had it now don't work at all...