Stater voltage

[krovar]

what should the voltage be between the two brown wires when cranking, i was told it should be atleast 180 ac volts i only have 95 new stater whats up PLEASE HELP cuts out bad over 3500 rpm and will only do 3700

 

[boobie]

Re: Stater voltage

Model # ??. Those voltages are read with a peak reading volt meter or a regular one with a dva adapter.

 

[krovar]

Re: Stater voltage

its a 1977 johnson 115 four cyl

 

[boobie]

Re: Stater voltage

Will your spark jump a 7/16" open air on all 4 cyls when cranking??

 

[metriccrescentwrench]

Re: Stater voltage

Why do you think the problem is your stator and not something else?

There's not much to the stator (it's just a long piece of wire wrapped around iron cores), so not much can go wrong except for coils shorted together or shorted to ground. Check resistance to ground (brown wires to ground), it shouldn't show anything (infinite resistance). Then check resistance of the stator charge coil winding (brown wires), on my '81 90 HP crossflow (I think your engine will be the same) it's spec'd as 560 +- 75 Ohms.

If you can round up a DVA adapter or peak reading voltmeter the output voltage is spec'd at 160 or greater (and that is NOT the same as AC volts).

There are a lot of other things that can cause your problem. Fuel flow. Dirty carbs. Timer base. Flywheel magnets. And I'm sure others can add more to the list.

 

[krovar]

Re: Stater voltage

very little spark the old stater looks like someone took a cutting torch to it put a volt meter between the to brown wires you get 95 volts rev the engine to around 1500 rpm voltage starts dropping to 85 volts and lower

 

[metriccrescentwrench]

Re: Stater voltage

very little spark the old stater looks like someone took a cutting torch to it put a volt meter between the to brown wires you get 95 volts rev the engine to around 1500 rpm voltage starts dropping to 85 volts and lower

But you said you're measuring AC volts, that won't tell you anything. You need a peak reading voltmeter, or else a DVA adapter, to get a proper reading. What those do is measure the peak of the "sine" wave produce by the stator.

If nothing else do the resistance tests on your stator. Measure the resistance between one of the brown wires and ground, resistance should be infinite. Then measure the resistance between the two brown wires, resistance should be 560 Ohms plus or minus 75.

 

[F_R]

Re: Stater voltage

The first indication of a bad stator is the motor won't start, but runs if you do manage to get it started. Your motor starts. I very seriously doubt the stator is the problem. But have to agree, you need a DVA peak reading voltmeter to measure it.

 

[krovar]

Re: Stater voltage

im confused i have a guy that all he works on are johnson he has been doing this for 40 years he said it dont need to show a short and can show the right resintance but still be weak and drop voltage at higher rpm causing missfires asked about the dva meter he looked at me funny and said thats what they used in the old days said just use a good volt meter on ac side between the two wires wile cranking and if its not atleast 180 ac volts the stater is bad or weak, called two other shops they told me the same thing i just dont want to spend 400 dollars for something i dont need.

 

[metriccrescentwrench]

Re: Stater voltage

Out of curiosity, have you measured the resistances yet? From your description it's possible the stator coil is shorted to ground, which will difinitely show up with an ohmmeter.

 

[krovar]

Re: Stater voltage

yes it shows no short from brown to brown 468

 

[F_R]

Re: Stater voltage

im confused i have a guy that all he works on are johnson he has been doing this for 40 years he said it dont need to show a short and can show the right resintance but still be weak and drop voltage at higher rpm causing missfires asked about the dva meter he looked at me funny and said thats what they used in the old days said just use a good volt meter on ac side between the two wires wile cranking and if its not atleast 180 ac volts the stater is bad or weak, called two other shops they told me the same thing i just dont want to spend 400 dollars for something i dont need.

Old days huh? Well ok I admit I'm kinda old. You have two opinions here. Accept the one you want to hear.

 

[wilde1j]

Re: Stater voltage

To each his own ... BTW a DVA adapter is under $30. I'm kinda old too and DVA is not "from the old days". It's the smart diagnostic tool. I'd just start replacing ignition stuff. You'll fly right on by $400 pretty quick, but eventually you'll have a brand new motor.

 

[boobie]

Re: Stater voltage

I agree with both F_R and Wilde1. Very well put!!!

 

[HighTrim]

Re: Stater voltage

I must be getting old, when I read the title, thought we were talking about a STARTER here, not stator, and was pretty confused, which is not hard to do.

I did not see you answer whether the spark is properly jumping a gap on all cylinders? What is the compression? I personally would start with the basics here. F_R used to work on the Ark, he is old, he wont guide you wrong.

 

[emdsapmgr]

Re: Stater voltage

The 77 service manual indicates that an ohms test is the correct way to discover a faulty charge coil. I've ohm'd a number of charge coils with inconclusive results. Probably my inaccurate testing methods. The later crossflow service manuals (at least by the 86 model year) offer a second method to test/qualify stators. That being to check the voltage output with a special peak-reading type voltmeter. In 1986, the output voltage should be at least 150 volts on a V4 at cranking rpm's, or the stator should be condemned. I've had accurate results with that method. Just not sure if it specifically applies all the way back to the 1977 system. Perhaps one of the experts can comment on this.

 

[boobie]

Re: Stater voltage

1977 was 160 volts cranking or higher.