Will Tachometer work if Stator is bad?

[Mark42]

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.

It uses a Blocking Diode. I was able to test it, and it passes OK. Thanks for posting that info about diodes, I didn't know they came in different flavors.

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.

Faztbullet, thanks for posting that test. I will do it tomorrow after Church. Will keep plugging away at this until the culprit part is identified.

Once again, the motor went into SLOW mode (or a good simulation of slow, HA!), This time I disconnected the temp senders (both) turned off ignition, and started again. IT MADE NO DIFFERENCE!!!! Still ran bad. So I bring boat home. By later afternoon, its cool and starts and runs smooth on the hose. So I intentionally ground the temp circuit, and the System Check temp light went on, the horn sounded for about 30 seconds, and the motor ran NORMAL!!! I thought it would instantly start running crummy, but there was no change. Although grounding the white/black temp wire does kick down the idle as the power pack thinks the motor is warmed up.

I'm beginning to think that the power pack may be bad, because when the motor starts breaking up and running bad, NO system check lights come on, and no horn sounds. When I test the temp circuit by grounding the tan wire, the horn sounds and temp light comes on. So its not a " bad temp sender is kicking the motor into SLOW mode." problem.

I did remove the coils, power pack and optical sensor cover to check all the connections and ensure nothing was obviously shorted. Cleaned the contacts and ground lugs with a course stainless steel scrub pad and reassembled. Everything looks good in this area, but it made no difference in the run test.

Also did a compression test and got 145psi on all 4 cylinders, although i think my gauge reads on the low side. At least all the cylinders are the same, and plugs look the same.

I'll do the regulator tests and let you know how it goes.

 

[tx1961whaler]

Re: Will Tachometer work if Stator is bad?

Is this a FICHT?

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Is this a FICHT?

No, just 2 stroke, carbed with optical spark.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Rectifier/Regulator Bench Test Results:

All tests done with multimeter set to 20M.

The regulator in the motor has the purple wire meaning its an older model regulator, newer model regulators do not use the purple wire. The purple wire supplies +12V to the regulator when the ignition is "on". The manual states " Models w/purple wire: The rectifier/regulator requires 12 V from the purple lead to operate. If the purple wire does not provide 12 V to the rectifier/regulator, it will not turn on and will not charge the battery". With the ignition on, there is 12.34 volts on the purple wire.

Diode Plate Test:
- Yellow wires to Red: 1.0, 1.0 w/+test lead to red. 0.79, 0.81 w/+test lead to yellow.
- Yellow wires to ground: 1.45, 1.39 w/+test lead to yellow, 2.30, 2.32 w/+ test lead to ground.
- Red to Ground: 3.35 w/+test lead to ground, 1.0 w/-test lead to ground.

Tach tests:
- Gray to red: 3.35
- Grey to yellow 1.39, 1.45 w/+test lead to yellow, 2.28, 2.30 w/+test lead to gray.

I think these are good results, but I don't understand why there is a difference in resistance readings when the test leads are reversed. I would think the readings would be the same. I'm using a Greenlee digital multitester DM-40 that is about 3 years old and has a fresh battery.

Then I re-tested the Stator resistance and I'm not sure what to make of the readings:

Stator test:
- yellows to ground 1.00, 1.00 (at any meter setting)
- Yellow to Yellow. At 20M setting, reads 0. At 200 setting, reads 00.1 (adjusted for test leads resistance of 00.3) Spec is 0.185 +- 0.01. Is this a bad stator or bad reading?

Then I grab my other mult-tester (Greenlee DM-50) and test the stator again. The leads on this tester touched give a reading of 0.004 at 2K. The yellow to yellow test shows 0.004, which would indicate zero resistance, right?

So now I am confused.

 

[sschefer]

Re: Will Tachometer work if Stator is bad?

Not sure if this will help but I'll throw it out there anyway.

A stator coil is copper wire wound around a core. The wire is coated with a clear insulating material so that it remains a long single piece of wire even though it is physically touching the other wire in the coil.

All wire has some resistance and that resistance grows with the length of the wire because resistance is directly proportional to the length and cross sectional diameter of the wire. Longer length = more resistance, larger cross section = less resistance. When you check resistance the manufacturer is telling you that for that given length of wire the average resistance should be xxx ohms. If it's less than it's likely that the wire coating has been damaged and the short between two or more windings is making the total length of the wire shorter. If the resistance is more then it would indicate that the wire is not properly conducting due to any number of reasons.

Most stators have multiple coils. In some cases, there are separate coils for charging and ignition. When you check the resistance at the coil leads, you'll be checking the entire length of the wire in all the coils of the particular circuit, (charging or ignition). I think you can see now why there is such a small allowable difference when your dealing will a multiple coil charging system or ignition system and why these tests are good for a failed system but not so good for one that is just beginning to fail.

The best test would be done with a time division reflectometer (tdr). You would have to know the exact length of the wire in each coil and then using a tdr, determine if the total lenght of the wire was the combined length of all the coils. This would tell you if your stator is good or bad almost instantly. But, not many of us have a TDR and the wire length is not often available.

On the bright side, if your simple voltmeter is showing charging circuit output (dc side) of between 13.5 and 15.5 volts then you can pretty much call it good.

 

[sschefer]

Re: Will Tachometer work if Stator is bad?

On the other side of the coin, most stators also contain ignition coils. Since the RPM range is pretty wide and space under the flywheel is limited, two ignition coils are often used. Both the magnets and coils have a static maximum current/voltage capability by design. The first coil provides adequate voltage and current up to about 2500 RPM and then starts to fall off. The second coil starts to come on around 2500 RPM and remains adequate up to about 6500 RPM. This is just a typical setup and may not be your specific configuration but I think you might be able to see a correlation here.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

rectifier/regulator bench test results:

all tests done with multimeter set to 20m.

The regulator in the motor has the purple wire meaning its an older model regulator, newer model regulators do not use the purple wire. The purple wire supplies +12v to the regulator when the ignition is "on". The manual states " models w/purple wire: The rectifier/regulator requires 12 v from the purple lead to operate. If the purple wire does not provide 12 v to the rectifier/regulator, it will not turn on and will not charge the battery". with the ignition on, there is 12.34 volts on the purple wire.

Diode plate test:
- yellow wires to red: 1.0, 1.0 w/+test lead to red. 0.79, 0.81 w/+test lead to yellow.
- yellow wires to ground: 1.45, 1.39 w/+test lead to yellow, 2.30, 2.32 w/+ test lead to ground.
- red to ground: 3.35 w/+test lead to ground, 1.0 w/-test lead to ground.

Tach tests:
- gray to red: 3.35
- grey to yellow 1.39, 1.45 w/+test lead to yellow, 2.28, 2.30 w/+test lead to gray.

I think these are good results, but i don't understand why there is a difference in resistance readings when the test leads are reversed. I would think the readings would be the same. I'm using a greenlee digital multitester dm-40 that is about 3 years old and has a fresh battery.

Then i re-tested the stator resistance and i'm not sure what to make of the readings:

Stator test:
- yellows to ground 1.00, 1.00 (at any meter setting)
- yellow to yellow. At 20m setting, reads 0. At 200 setting, reads 00.1 (adjusted for test leads resistance of 00.3) spec is 0.185 +- 0.01. Is this a bad stator or bad reading?

then i grab my other mult-tester (greenlee dm-50) and test the stator again. The leads on this tester touched give a reading of 0.004 at 2k. The yellow to yellow test shows 0.004, which would indicate zero resistance, right?

So now i am confused.

ttt

 

[Faztbullet]

Re: Will Tachometer work if Stator is bad?

On the other side of the coin, most stators also contain ignition coils. Since the RPM range is pretty wide and space under the flywheel is limited, two ignition coils are often used. Both the magnets and coils have a static maximum current/voltage capability by design. The first coil provides adequate voltage and current up to about 2500 RPM and then starts to fall off. The second coil starts to come on around 2500 RPM and remains adequate up to about 6500 RPM.

Only Merc's use this type stator, the OMC's have a charge coil for each bank and a charging winding to charge battery. Your test of stator are good(anything near infinity) but be dont pass the rectifier off as good yet as the ignition powered one gave the most problems.The new replacement rectifiers do not use the purple wire anymore due to their problems....

 

[Chris1956]

Re: Will Tachometer work if Stator is bad?

Fazt, Doesn't that motor have a water cooled voltage regulator, vs a rectifier?

 

[Faztbullet]

Re: Will Tachometer work if Stator is bad?

Yep ...35 amp water cooled rect/reg

 

[sschefer]

Re: Will Tachometer work if Stator is bad?

Only Merc's use this type stator, the OMC's have a charge coil for each bank and a charging winding to charge battery. Your test of stator are good(anything near infinity) but be dont pass the rectifier off as good yet as the ignition powered one gave the most problems.The new replacement rectifiers do not use the purple wire anymore due to their problems....

Wasn't aware of that, thanks.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Called the rebuilder today, they are sending a new power pack. Might just order two new coils and 4 wires to go with the new power pack. But first, I'll see how the power pack performs on its own.

Will keep you posted.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Just a quick update on this thread....

Got the new CDI Power Pack from the rebuilder.

I had also decided to replace the rest of the electronics with new parts just for the sake of reliability. So I ordered and received two new coils and a voltage regulator. Also bought a used stator off ebay for cheap just to have a backup. Will install all this stuff (except the stator) this evening or tomorrow and see how the boat runs this weekend.

While rummaging through some stuff, I came across a bunch of old Force parts. Put them on ebay, and so far, the sales have covered the cost of the extra parts I bought for the 90. Sometimes things just work out well.

I hope this is the end of it. I want to finish breaking in this motor and hit the bay.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

Update: This morning I finished installing the new Power Pack, Regulator, and coils. Tested voltages as per CDI instructions, then hit the water.....

SUCCESS!!! Ran the boat for 3 hours. It ran well, and right away I could tell the difference in how the motor ran. First, it ran at high idle on its own for about two minutes, then dropped down to normal idle as it warmed up. Just as it is supposed to. And under load, it was smoother running and felt more powerful than previous outings. Small changes in throttle made a bigger change in power than before. So I'm convinced that the power pack was failing and not performing properly across the board, not just when it heated up.

Also noticed that the Volt gauge was indicating smooth sweeps in volt changes, and always registered above 12 volts, and never over 14.5 volts. Before installing a new regulator, the gauge would often sit at 12.5 volts, then jump up to 14-15 volts, then drop back down to 12. Very jumpy, not smooth. So the voltage regulator was failing as well as the power pack.

The end result is a nice mechanical rebuild, with new VRO2 pump, new power pack (about $500 worth of parts, both courtesy of Blackbird) and I supplied new voltage regulator and two new coils. So I'm pleased with the end result. Although it would have been better if it all worked right last September!

BTW, the few times there was smooth enough water to run WOT for a minute, the RPM topped out at 4600-4700. The specs say to run the motor between 4500-5500 at WOT. I would like to have the motor closer to 5500 than 4500, but the next lower pitch prop (19) lets the motor over-rev. So I guess I'm stuck with the 21 pitch and 4700 rpm max? Maybe I can play with the trim and get a few more PRM out of it at WOT??

Thanks to all who contributed to this thread. Every bit of knowledge/info helps!

 

[hidef]

Re: Will Tachometer work if Stator is bad?

A 19" pitch prop should only raise your RPMs by 300 placing you at 5000 RPM you should be able to safely spin a 17. Keep in mind if your 21" prop is stainless than the 19 or 17 should also be stainless for these numbers to be correct. if you went to 19" aluminum wheel than you would be looking at 500 rpm difference from a 21 stainless to a 19 aluminum.

It sounds like you voltage regulator was the culprit. The first thing CDI tells you to do is to disconnect the voltage regulator and see how the engine runs. I just suffered through the same issues as you this past week. Fortunately I had the manuals and tools with me and I was able to troubleshoot the the problem.

 

[Mark42]

Re: Will Tachometer work if Stator is bad?

A 19" pitch prop should only raise your RPMs by 300 placing you at 5000 RPM you should be able to safely spin a 17. Keep in mind if your 21" prop is stainless than the 19 or 17 should also be stainless for these numbers to be correct. if you went to 19" aluminum wheel than you would be looking at 500 rpm difference from a 21 stainless to a 19 aluminum.

.

Thanks for reminding me about the RPM change per pitch.... You are right! The 19 should be working fine. Don't know why I thought it was running too high.... I have both 19 and 21 pitch props, so I'll have both of them with me next time I hit the water, and will switch back to the 19 for the next run.

It sounds like you voltage regulator was the culprit. The first thing CDI tells you to do is to disconnect the voltage regulator and see how the engine runs. I just suffered through the same issues as you this past week. Fortunately I had the manuals and tools with me and I was able to troubleshoot the the problem.

Could have been, but the motor always died after the same period of time, regardless of whether or not the regulator was working at the time. Pointed to the power pack heating up and failing.

Thanks!

Mark