1986 50hp rectifier voltage? too low?

[dkonrai]

my 86' 50 hp, wasnt charging the battery. so i checked the battery cables, and i had only 12 volts, when i revved the engine there still was no change in voltage.

changed the rectifier, and now it reads 12.4 volts at idle. when i give it some gas, i get 12.7 volts. i have not checked it on the water at wot. is this normal?

thanks
dino

 

[pnwboat]

Re: 1986 50hp rectifier voltage? too low?

12.7 D.C. output from the rectifier is low. Should be more like 13.5 volts D.C.

Check the voltage output from the stator to the rectifier. You should read A.C voltage here. About 15 - 16 volts A.C.

Also check the stator resistance with the ohm meter. Blue and yellow wires. Should read 500 - 1000 ohms.

Also check between ground and the blue and yellow wires. Should read open.

 

[chuckz]

Re: 1986 50hp rectifier voltage? too low?

The voltage only tells part of the story. if your battery is not fully charged, this may be OK. You need to check and see what the current to the battery is. If you have more than 10 amps, the battery is taking a pretty heavy charge and the voltage will rise as the battery charges..

 

[dkonrai]

Re: 1986 50hp rectifier voltage? too low?

12.7 D.C. output from the rectifier is low. Should be more like 13.5 volts D.C.

Check the voltage output from the stator to the rectifier. You should read A.C voltage here. About 15 - 16 volts A.C.

Also check the stator resistance with the ohm meter. Blue and yellow wires. Should read 500 - 1000 ohms.

Also check between ground and the blue and yellow wires. Should read open.

thanks i will give this a try. how do i check the ground and the blue and yellow wires?

also, the battery was not fully charged, it was partial at 12 volts. too lazy to put it on the charger.

 

[chuckz]

Re: 1986 50hp rectifier voltage? too low?

If you know your battery was low, the system is probably working fine. Charge your battery and recheck the voltage or run the boat and as long as the battery voltage keeps rising, you're OK. Or measure the charge current if you know how. If you have charge current, you're OK.

 

[pnwboat]

Re: 1986 50hp rectifier voltage? too low?

Do you have points for the ignition system or CD Modules? I may be steering you wrong on the color code depending on which one you have. My apologies.

The color for the wires that is the A.C voltage from the stator are probably green with a yellow stripe. These two wires should go to the rectifier. These two wires is where you want to check the A.C. voltage. 15 - 16 volts A.C. here with the motor running at a minimum of 2000 RPM's. Might take 15 or 20 seconds at a minimum of 2000 rpm's before you see the correct voltage.

 

[dkonrai]

Re: 1986 50hp rectifier voltage? too low?

pnw,
unfortunately, i dont have a tach. so i will need to go by ear

system is cdi, no points and the coils are a little old

coils

old rectifier

i bought a new one from radio shack. i figured if i can get the charging system to work, i will flip for the regulator. i should check the voltage at the ac side of the rectifier?

question, if i dont get the 13 volts, does this mean i have probs with my stator? the engine fires good, excluding the off idle i have cleaned the carb twice and it still runs a little rich.

 

[pnwboat]

Re: 1986 50hp rectifier voltage? too low?

Hmmmm....looks like all of your wires are red! Make sure the two red wires that come from underneath the flywheel (these most likely come from the stator) are connected to the posts on the rectifier that are marked "AC". This is where you should read 15 - 16 volts A.C. with the engine running at 2000+ RPM's. If you don't see the proper AC voltage, you can test the stator winding by ohming them out. Disconnect them and you should read about .5 ohms across the two wires. If you read higher than that, the battery charging windings are probably bad on the stator.

There's something odd about the color of the wires coming from the stator. Maybe someone has monkeyed around with the stator? They should be green w/yellow stripe.

There's also something else that doesn't look right. The gray wire attached to the post with the black ground wire. I don't think it's supposed to be there. It looks like it also goes to the stator. I don't think any of the stator wires are supposed to be connected to ground. Can you confirm where that gray wire comes from?

Did a little research and it appears that the color may be correct.

 

[dkonrai]

Re: 1986 50hp rectifier voltage? too low?

pnw,
thanks for the reply. i will take more photos tomorrow, as long as it doesnt rain..... i live in northern cal, and it has been raining pretty much non stop.

when testing the stator wiring, should i test the ac leads, and then place the black (tester) wire to a ground?

 

[pnwboat]

Re: 1986 50hp rectifier voltage? too low?

No, put one meter lead on one of the AC terminals, the other meter lead on the other AC terminal.

One other question. Where were you measuring the 12 volts? At the battery, or at the rectifier?

 

[dkonrai]

Re: 1986 50hp rectifier voltage? too low?

pnw
i measured 12v at the battery terminal. actually 12.3 as i slowly revved the motor the voltage raised with the rpms. i was testing the motor in a garbage can of water, and really dont know what the voltage is when mid or wot.
dino

 

[chuckz]

Re: 1986 50hp rectifier voltage? too low?

It's working, stop troubleshooting. The Radio Shack rectifier does not have to be replaced. It's the same as the OEM part. The voltages you are being told to check will be present with a fully charged battery. The voltage is going up when you rev the engine because the current is increasing, its working.

 

[pnwboat]

Re: 1986 50hp rectifier voltage? too low?

After you get the battery charged, double check the D.C. voltage at the rectifier to see if the readings are the same as at the battery.

 

[dkonrai]

Re: 1986 50hp rectifier voltage? too low?

thanks guys. i will keep everyone posted of the results.