97 Johnson 35hp 3cyl regulator/rectifier trouble.

[Magget]

Just need to double check with you guys before I order a new regulator/rectifier unit.

I bought a used 1997 35hp johnson that run fine but has some issue with the tach, it shows rpm on idle and up to about 1800rpm then settles at zero until I back off the gas and it starts to live at 1800 again and backs down to idle.

I tried measuring the stator using a digital multimeter according to joereeves guide, set to the diode check setting no wires seemed to register on the meter but when I changed it to resistance it read between 300-500ohm on all cables in one way and infinate in the other except when I checked between the two yellow wires and the "box" (ground I guess) that showed 300ohm one way and about 500ohm the other way. this seems awfully high to me but I don't want to replace the part if it's still fine. What do you think about it?

Best regards
//Magnus

 

[racerone]

What is the reading in ohms on yellow wire to yellow wire ?---------What is the ohm reading on one yellow wire to ground ?-------If the oil injection unit is still on the motor it should be taken off and thrown away !

 

[Magget]

What is the reading in ohms on yellow wire to yellow wire ?---------What is the ohm reading on one yellow wire to ground ?-------If the oil injection unit is still on the motor it should be taken off and thrown away !

I don't think I checked it but yellow to ground was about 300 in one direction and 500 in the other on both yellow wires.

I also forgot to mention that the motor doesn't charge the battery.

 

[racerone]

The factory manual has this info.--------------Yellow to yellow gray should read 0.45 to 0.54 ohms.

 

[Magget]

The factory manual has this info.--------------Yellow to yellow gray should read 0.45 to 0.54 ohms.

Thanks! I'll check that when I have the chance.

 

[racerone]

Yellow to yellow / gray on the stator should read that value in post # 4

 

[papyson]

typical rectifier failure when the tach acts like that...it will eventually fail completely...do you have a rectifier only charging system or a regulator? if its a rectifier only one what battery are you using?...these systems dont like a maintenance free sealed one..

 

[Gary Vinzant]

Is the motor running ok? Is there a cylinder misfire? When my rectifier went bad I lost fire to the #4 cylinder and only that cylinder. Good thing a rectifier is relatively cheap and if you are not charging anymore chances are its bad

 

[racerone]

Rectifiers on these 3 cylinder motors are not cheap !!!

 

[Gary Vinzant]

Oh I was going by what I paid for mine lol... I think I got mine for $34

 

[Magget]

typical rectifier failure when the tach acts like that...it will eventually fail completely...do you have a rectifier only charging system or a regulator? if its a rectifier only one what battery are you using?...these systems dont like a maintenance free sealed one..

Ok. I've been using an AGM battery. Should I change it for another type?

It's a combined rectifier/regulator unit.

 

[Magget]

Is the motor running ok? Is there a cylinder misfire? When my rectifier went bad I lost fire to the #4 cylinder and only that cylinder. Good thing a rectifier is relatively cheap and if you are not charging anymore chances are its bad

Yes, I have a missfire issue too but figured that came from a bad connection in one of the spark cables.

 

[papyson]

if the battery is sealed then change it out...

 

[Magget]

if the battery is sealed then change it out...

Can the AGM battery damage the rectifier?

 

[papyson]

if it has a regulator then its ok to use this battery...