no charge on 120hp.

outlander 1 · May 2, 2010

i have a 1991 120hp force outboard motor that does'nt charge my battery when running...i check the obvious, connections, fuses, etc...i believe at one time a battery charger was hooked up backwards....what would doing this, fry. could you help me in locating this problem and what to check....thanks

john from md · May 2, 2010

Re: no charge on 120hp.

First, if your battery is not new, take it to Pep Boys, Advance Auto or Walmart and have it tested. No sense spinning your wheels with a battery that is not up to snuff.

Second, clean all of your battery contacts well.

Next, hook a voltmeter accross the battery and see what it reads at 2000 rpm. It should be in the area of 13-14 volts.

Let us know what you get.

John

outlander 1 · May 2, 2010

Re: no charge on 120hp.

thanks for replying....battery is new, contacts are clean..there is no increase in voltage in the battery when i'm running at any rpm...what wire from the engine is used to charge the battery...is it the large red one??

john from md · May 2, 2010

Re: no charge on 120hp.

The red wire from your regulator goes to the solinoid where it connects with the heavy red wire to the battery. Your regulator is a small grey box with four wires coming out of it. Two are yellow, these are AC voltage from the stator, one is red, this is the DC output to the battery and the other is grey which is your rpm impulse to your tach.
Try connecting the voltmeter accross the two yellow wires that go to the regulator. The easiest place to do this is on the terminal board. Set your voltmeter for AC. If you get increasing voltage when you increase the power setting, replace the regulator.

John

outlander 1 · May 3, 2010

Re: no charge on 120hp.

thanks for great input....when you say increase the power setting, what do you mean? thank you

john from md · May 3, 2010

Re: no charge on 120hp.

When you move the throttle from idle to WOT.

John

outlander 1 · May 3, 2010

Re: no charge on 120hp.

thanks...i'm gonna try that..so the only thing it really could be is the voltage regulator..

john from md · May 3, 2010

Re: no charge on 120hp.

If you are getting 18-20 VAC out of the stator and the battery is showing less than 14-14.5 VDC then, barring wiring problems, the regulator is fried.

This usually happens if you have alot of electrical equipment, sterios, depth finders etc and you have a standard size battery and do more than usual starts. A group 29 battery will usually correct the problem after the regulator is replaced of course.

John

PaulO · May 3, 2010

Re: no charge on 120hp.

John from MD

I started my motor for the 1st time on the weekend. I couldn't get a volt reading of more than 12.5 at the battery (with the shift lock in place) but I could get 13.5volts at the terminal block containing the red wire from the regulator. When I moved the probe further down the red wire line to the main terminal block It would read no more than 12.5V ?.2V. I am at a loss at the moment.

I see your text that says the red regulator wire is connected to the solenoid which I presume you mean starter solenoid? I feel mine is different and will check. Based on the 13.5 volts of the regulator, is it fair to say it is working correctly?

PaulO · May 3, 2010

Re: no charge on 120hp.

I tested the Stator resistance = .7 OK
Tested the two yellow wires into the rectifier/regulator with reverse polarity and no discernable difference. It should read high and low.

Will any automotive rectifier/regulator do?

pnwboat · May 4, 2010

Re: no charge on 120hp.

No, but one from Radio shack will work. 25A full bridge rectifier. Or if you really want to get fancy you can install a rectifier/regulator. See John from MD's sticky at the top of the Forum list regarding "If you have high charge voltage"

john from md · May 4, 2010

Re: no charge on 120hp.

The red wire from the rectifier feeds the red battery wire on the solinoid. This may be connected through the terminal board.

If you are getting 13.5 at idle from the rectifier and 12 downstream of the rectifier, it sounds more like corrosion to me and not a bad rectifier.

John

PaulO · May 4, 2010

Re: no charge on 120hp.

John from MD

The test on the 2 yellows to the rec/reg was a procedure described in the clymer's manual. I got a resistence of 9.87 with the meter terminal on earth and yellow and the same when the meter terminals were swapped over on the same wires. The book said one way will be high the other will be low. That goes for both AC inlet (yellow) wires.

The engine is pretty clean and has just been rebuilt. The red wire does go to the starter solenoid too. I thought I may have missed that one.

The only other thing to do is recheck the cleanliness of the terminals on those wires and the earth contacts on the electronics board.

john from md · May 4, 2010

Re: no charge on 120hp.

I re-read your post about the voltage readings you were getting. On the terminal board you were getting 13.5 and 12.5 further down the line. This has to be a high resistance between the two points you checked. Run a jumper wire between the two points and see what happens. You may have corrosion inside the insulation of the wire.

John

PaulO · May 4, 2010

Re: no charge on 120hp.

Good Point! I will check it out.

no charge on 120hp.

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