Will Tachometer work if Stator is bad?

[Mark42]

If the stator is bad on a 2003 90 hp, and the motor is running off battery power, will the tach continue to work? (ie still get pulses from the 12 pole stator)?

Or will the tach register nothing?

BTW, I did the resistance check on the stator and it registers OK on the multi-tester. But that doesn't guarantee that it isn't failing once it gets hot or vibration causes a short. (right?)

 

[ezmobee]

Re: Will Tachometer work if Stator is bad?

My understanding has been that no, it won't.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

My understanding has been that no, it won't.

Thanks EZ!

I think the stator is OK, just wanted a "second opinion".

 

[Chris1956]

Re: Will Tachometer work if Stator is bad?

Mark, Most outboards do not run off battery power. The run off seperate windings on the stator that power the "powerpack". Other stator windings provide power to the charging system. These "charging" windings typically provide the tach signal. I suggest you consult a wiring diaghram for your motor. I think you will see a connection from the starter solenoid circuit to the powerpack, but no connection from the engine accessory circuit to the powerpack. This kind of wiring allows battery voltage to go to the powerpack when the motor is cranking only. Once running, the battery plays no role in ignition.

 

[wilde1j]

Re: Will Tachometer work if Stator is bad?

agree

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Mark, Most outboards do not run off battery power. The run off seperate windings on the stator that power the "powerpack". Other stator windings provide power to the charging system. These "charging" windings typically provide the tach signal. I suggest you consult a wiring diaghram for your motor. I think you will see a connection from the starter solenoid circuit to the powerpack, but no connection from the engine accessory circuit to the powerpack. This kind of wiring allows battery voltage to go to the powerpack when the motor is cranking only. Once running, the battery plays no role in ignition.

I have the Johnson Service manual and checked the wire diagram as you suggest. You are correct, there is no direct 12v feed to the powerpack (except when the starter relay is engaged). The manual also says there are Charge coils and Power coil on the stator. One is for the charging system, the other for the power pack.

So what does this mean in relation to the volt gauge readings I posted above?

Thanks!

 

[Chris1956]

Re: Will Tachometer work if Stator is bad?

Mark, I am not sure I understand your question. I believe that any of the coils on a stator could go bad. So you could have ignition, but no charging, or no ignition and still have charging, or neither.
BTW - I did not see any volt gauge postings.

 

[SparkieBoat]

Re: Will Tachometer work if Stator is bad?

Mark, I have found OHM test on outboard electronics to be very unreliable. I use a DVA adapter with my multi meter and have been able to accurately diagnose many outboard problems without guessing. a free trouble shooting guide is in my sig below

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Mark, I am not sure I understand your question. I believe that any of the coils on a stator could go bad. So you could have ignition, but no charging, or no ignition and still have charging, or neither.
BTW - I did not see any volt gauge postings.

The boat stalls out after about an hour run time. I am sure at this point it is not a fuel issue. The tach works 100% of the time. The volt gauge sometimes reads 12v, then will suddenly jump to 14 and 15 volts, then a few minutes later, drop back to 12 v. (When its at 12v, the gauge pointer it sits at the same location as when the ignition is on, but motor is not running, so I think its just showing battery voltage when its at 12v.) Motor is pumping lots of water at 15-20 psi with new impeller. The power head is rebuilt, but the electronics are the original. Trying to determine where the problem is, stator, power pack, coil, etc. The last 3 times I went out, it stalled out after almost 1 hour exactly each time. After 1 hour it will start misfiring bad, drop to a rough idle, and stall after 10-20 seconds of running. It will not rev up because its misfiring so badly. It restarts, and pumping the primer makes no difference. Disconnecting spark plug wire seems to indicate that port top and starboard bottom cylinders are misfiring. But its hard to tell because the motor is running pretty crappy at that time. For the first hour or so it runs great, pulls hard, and runs smooth. The next day, it will start, run great for an hour, then starts misfiring again.

Mark, I have found OHM test on outboard electronics to be very unreliable. I use a DVA adapter with my multi meter and have been able to accurately diagnose many outboard problems without guessing. a free trouble shooting guide is in my sig below

Thanks for the link. I will check it out.

 

[Chris1956]

Re: Will Tachometer work if Stator is bad?

Sounds like you need an OEM Service manual. I would check/disconnect the SLOW feature to make sure that is not causing/increasing your problem. Also make sure the motor is not overheating. Have you inspected the thermostats?
You can put some ice on the powerpack to help isolate any heat related ign issues.

BTW - that high water pressure you are seeing is normal.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Sounds like you need an OEM Service manual. I would check/disconnect the SLOW feature to make sure that is not causing/increasing your problem. Also make sure the motor is not overheating. Have you inspected the thermostats?
You can put some ice on the powerpack to help isolate any heat related ign issues.

BTW - that high water pressure you are seeing is normal.

I have the OEM service manual. But I don't see anything about disconnecting the SLOW system in the manual. Can you post how this is done?

This weekend I am going to remove and test the thermostats, and also the temperature senders, and (even though the system check lights go through the startup check OK) will test that the system check light goes on when the temp senders are grounded.

Thanks for the suggestions.

BTW, what size socket fits the thermostat cover? Not the smaller inside hex, but the outer size, probably in the 2" range. Going to have to buy a socket that size.

 

[daselbee]

Re: Will Tachometer work if Stator is bad?

Mark, I have found OHM test on outboard electronics to be very unreliable. I use a DVA adapter with my multi meter and have been able to accurately diagnose many outboard problems without guessing. a free trouble shooting guide is in my sig below

Very true advice regarding the OHMs testing. Best to use a DVA, measure voltages. Good advice Sparkie.

 

[Chris1956]

Re: Will Tachometer work if Stator is bad?

Mark, The SLOW system is activated whenever either of the two temp sensors is grounded. if you disconnect the wire that connects them to the powerpack, SLOW should be disconnected. of course I would make sure the 'stats are good forst, so you don't risk overheat.

Remember one of the temp sensors also activates the Quickstart system, when the motor is cold.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Mark,..... .... a free trouble shooting guide is in my sig below

Thanks Sparkie! That has some info that is not in the OEM manual. Good to have.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Mark, The SLOW system is activated whenever either of the two temp sensors is grounded. if you disconnect the wire that connects them to the powerpack, SLOW should be disconnected. of course I would make sure the 'stats are good forst, so you don't risk overheat.

Remember one of the temp sensors also activates the Quickstart system, when the motor is cold.

Chris1965, I'm thinking (hoping) that this is the SLOW system kicking in because of a bad temp sender. So when the motor stalls out this weekend, first check will be to disconnect the sending wires, turn off the ignition and re-start. (but check for real over heat first, heads would be too hot to touch for more than a few seconds).

One would think that when slow kicks in (rpm limited to 2500) that the motor would still run smooth at low RPM. But the CDI doc that Sparkie has in his sig says the motor shakes really bad in SLOW mode. Mine is shaking really bad when its not running right. Hope its just a bad sender.

Thanks for the info!

 

[SparkieBoat]

Re: Will Tachometer work if Stator is bad?

CDI has really went the extra mile to help their customers, they will even give support over the phone if you cant figure something out, their parts seem to be as reliable and much cheaper than OEM parts also. So they have earned my business. Their troubleshooting guide is the best i have seen and it is FREE. If you look up the CDI part for your motor it will also have an install guide PDF file, that you can download free and it also has specific test for that part, sometimes includes things not in the guide.

 

[sschefer]

Re: Will Tachometer work if Stator is bad?

Mark, you can test this in the driveway on muffs. Just use a hair dryer and heat the suspect components. It's a Merc trick but it should work the same on a johnnyrude.

Also, your tach gets it signal from the charge coils on the stator. Most universal marine tachs have a pole switch on the back so they can be used with different stators. Sounds like your's is working but the regulator (if you have one) may be failing and that could be why your volt gauge is fluctuating. With the engine off and the key on the gauge should read approx 12v *(12.6 on a fully charged battery). It could also be as simple as a loose connection. Liquid tape can work wonders for keeping that in check.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Spent the whole evening pouring over the Johnson manual, CDI manual, and wire diagrams. One intersting bit of info I found in the Johnson manual sound like it applies to my situation. They say to check the diode in the power head wire harness (tan temperature sensors circuit) if the SLOW system is cutting in and no horn is sounded. I think that is the condition I have. BUT.... There is so little info on this specific test that I am not sure if they mean the bad diode can cause the SLOW to kick in AND no horn, or IF the SLOW kicks in, THEN the bad diode will prevent the horn.

At any rate, I will check the diode tomorrow. If its bad, I'm sure a 6Amp diode from Radio shack will suffice.

Anyone have any experience with a bad diode?

 

[sschefer]

Re: Will Tachometer work if Stator is bad?

Yep, diodes will only pass current in one direction. If you have a multimeter put it in continuity mode. Put the meter probes on the diode leads. It may show open or shorted. If you switch the leads it should be the exact opposite. In otherwords, shorted one way and open the other. If it happens to be a zenier diode (small clear looking thing) it will pass current in either direction but at different voltages. They're a litte harder to troubleshoot with a basic ohm meter. You need to have one with the diode setting.

If the standard diode shows continuity regardless of how the probes are hooked up then it's shorted. If it shows no continuity in either direction then it's open.

 

[Faztbullet]

Re: Will Tachometer work if Stator is bad?

The thing most overlooked on this post is the rectifier/regulator has a seperate output for tach signal. The rectifier/regulator can be good and tach sender signal side fail resulting in no or erratic tach operation. With battery voltage jumping around as you posted it possible that the rectifier/regulator has failed and causing stator to overheat,this will cause a miss as pack is not getting correct voltage from charge coils and the charge windings supply voltage for the battery charging. Here is how to bench test the rectifier....
Diode plate check: Test the forward diodes between the two yellow wires and the red wire just like you would on a regular rectifier. You should get a reading one way but not the other. Check the resistance from each of the yellow wires to case ground, you should have a high reading, typically in the M range. The red wire should not read to
ground or show a very high reading, 25M ohms or more.
B) Tachometer Circuit: Check the ohms resistance between the gray wire and engine ground. You should read approximately 10K (10,000) ohms. Gray to red, and gray to the yellow wires should be a high reading, usually in the M range.