Reverse polarity?

[rgpbeme]

I have a 96 gsx with 787 motor. With a fully charge battery i will run about 20 min. Then just die. will restart after setting go 100 yards and die
All low voltage related. I have checked the stator for out put and ground. Has fine ac voltage. Checked all wiring from Rectifier to stater. All fine. It is a 3 coil stator going to Rectifier.. While running with a hose I pulled the red feed off the Rectifier
The side that plugs into the Rectifier has battery voltage 13+ positive DC The side coming from the rec. varies according to RPM but it reads negative DC! I am using a very good multimeter. I have checked with several dealers and none have heard of this. I had a friend that works on boats check it also to see if I was doing something wrong.
He said he had a Mercury outboard do this once but could not remember what caused it. I don't want to just start throwing parts at it. PLEASE HELP
Also all fuses are fine.

Thanks Ron in Arkansas

 

[seadoosnipe]

Rectifier?

Then from what it sounds like, you've narrowed your problem down to the rectifier. And it makes you wonder if there is a way to reverse the polarity field on it. I've never heard of this either but it gives me something new to chew on.
I'll do a little reading on it and see what I can find out. In the mean time, look on the bottom of your forum page for the name "wheels and waves" or vice versa. His name is Don, send him a PM and ask him to look at your post. Maybe he's heard of this before. He's been a mechanic on Seadoo's for years and may have heard of this.
Louis

 

[rgpbeme]

Voltage

Thanks. The rectifier is new. The see doo was discharging the battery very fast so the test lead to a new rectifier. I did not check the old one for the reverse voltage and will do that. It is something I thought a dealer may have ran across so I called 6 in my area and nothing.

 

[Wheels & Waves]

I can't say that I have come across that either. When we check the charging system on that engine, generally we only have to do a static test and not dynamic testing. Usually the problem is either with the battery (will not load test properly), the reg/rect or the stator (charging coils). Most of the time the problem is the reg/rect. A couple of things to check and get back to me. First, check resistance between the Yellow wires of the stator. Check all to each other and post the readings. Also, check any one to ground and make sure there is no continuity to ground. Make sure you have a good ground from you batter - to the electrical box. The 787 is a DC CDI system and needs good grounds and voltage to run. Checking your battery, does the voltage drop more than 1 to 1.5 volts when you crank it?

 

[rgpbeme]

More test

Thanks for your reply I did some more test and below is the results

1. 3 yellow wires from stator each read 20-25 VAC when running and increase when motor is reved.
2. Meter at RX1 test between yellow stator wires all .50-.75
3. When running I have AC on red from rectifier and I have up to 15 volts neg DC both read when switched to that position on meter with 3 yellows hooked to rectifier.
4 From red on rectifier to yellow with male plug unplugged I get 0 at RX1 on meter. On other two with female plugs I get no meter movement.

I found the white coil wire on neg side of coil. My dia. does not show if coil is positive or negative ground.

When I plug the red output from the rectifier to the red wire to the Electronic Module it slows the motor enough to be noticeable

I got the same readings with the old rectifier

Thanks for the help
Ron in Arkansas

 

[seadoosnipe]

Manual?

Ron, do you have a manual? There is another member with an electrical problem and I've tried to help him. He's got the 94 GTX and has no spark at the plug and high ohms off the stator. His readings were within the manuals minimum and maximum output, so I was able to let him know that but that was pretty much all I could tell him.
The reason I bring it up is because in trying to troubleshoot the electricals, the high way map (schematics) offered in the manual along with the static and dynamic testing procedures are a real "+" in trying to solve a problem you can't see.
It may be worth the few dollars for you to become a premium member or look around to find a manual somewhere.
I'll be bumping this over to Don "Wheels and Waves" because I'm sure there is no further input I can give you.
Good luck and I hope your able to find a satisfactory solution. Please keep your post updated so other members who may run across the same problem may find help from your solution.

 

[rgpbeme]

Manual

With out steping on any toes because I don't know who handles manuals on this site. I have a great manual It even has sections on setting up for racing and how to true a hull It has sections on painting.

It was a $8.88 dollar down load of the complete shop,parts.racing and anything else you can think of.

It is from midwest manual on ebay. I don't think they are pirated either. They have hundreds of different ones.

 

[Wheels & Waves]

Let's get back to basic's....

I have a 96 gsx with 787 motor. With a fully charge battery i will run about 20 min. Then just die. will restart after setting go 100 yards and die
All low voltage related.

First, did you load test your battery? A bad battery can show good static voltage, but when a load (starter or other high amp load) is applied, the voltage will drop below normal. When the ski is running, do you have an increase in DC voltage at the battery? This should be around 13.5 volts. If you are getting this increased voltage at the battery, then your charging system is good. Your charging coils are checking OK when cold, but can be increasing in resistance when the coils get hot. As you know, when current passes through a coil, it warms up. If your stator is going bad, the problem could happen when they are getting hot. You can check this by carefully heating the mag cover with a heat gun while monitoring the resistance levels on the coils. Don't overlook the simple, basic problems as most of the time, these are the problems. BTW, a factory Sea Doo service manual is far better than anything else on the market. Who paints fiberglass anyway?

 

[rgpbeme]

Thanks again
I have used 2 different new batteries . both have been load checked.
Does the rectifier put out DC neg voltage on the red wire? Is that converted somewhere to charge the battery in the elect.box.?

With a fully charged good battery it will run about 20 min before it dies. It then has a "low 12 volts" on the panel. after it sits a while it will restart. When it restarts the low 12 v will go away . When it dies it will not even turn over will beep once. I pull the lanyard and will keep trying till I get two beeps then it will restart. Goes till it dies

The rectifier puts out up to 15 vdc neg. at the line right off the rectifier.


The manuals are sea doo. They just include more than a shop manual. The paint section is gives the product to use to fill any low spots how to sand the high the prep. how to true the hall for racing and the sea doo color

I am going to replace the stator as the next step

Thanks Ron

 

[Wheels & Waves]

I may have missed it, but did you ever check the voltage at the battery while running? If so, what was it?
If the voltage is good (around 13.5 volts at 3000 rpm) when the electrical system is cold, use that voltage as a reference and check again after you run it till it quits and restart it.

 

[rgpbeme]

What is the out voltage?

I have been to my local marine and have talked to him about the problem. His concern was what should the stator put out in volts. Everything I see is watts.
Almost everything he sees is in the 180 to 200+ volt range and the 25 volts sounded way low. How do you convert the watts to volts. I see the manual says 180 watts output for the stator.
Thanks Ron

 

[seadoosnipe]

Volts verses watts

Ron, voltage and wattage are two ways of measuring electrical power. Voltage as explained in the Webster's dictionary as the international system unit of electric potential and electromotive force, equal to the difference of electric potential between two points on a conducting wire carrying a constant current of one ampere when the power dissipated between the points is one watt.
Wattage as explained by the Webster's dictionary as an electrical power measurement as used in an electrical device.

So in short, the voltage is the power supply of different values where watts are a specific amount used in a particular device. For instance, you may have a light bulb in your lamp that operates the filament at 65 watts or a hair dryer that uses 1500 watts but they are both supplied by 120 volts AC.

If your taking measurements on your electrical system to troubleshoot, then on your multi meter, you have choosen to measure watts and not volts. The magneto is an electromagnetic generator that creates a high output of alternating current which is then converted to a low voltage/high amp direct current through the rectifier/regulator. This DC power is used to supply DC voltage to your battery, which in turn supplies the entire electrical system with about 13.5 vdc. .

You can check your charging system by selecting to measure DC voltage on your meter. Check the battery, it should be reading a little over 12 vdc. Then start your motor, if the charging system is working well, the measurement on your meter now should read about 13.5 vdc.

And he's right. The output of 25 volts is way to low. Unless he's measuring volts DC, then that means it's way to high. That would point to your rectifier/regulator being bad.

 

[rgpbeme]

thanks

Here is what I am trying to do. I want to start with the stator. I want to check each of the three legs to see it they are consistent. I need to find what the AC voltage should be right the from the stator before it goes to the rectifier. I think that would be a good starting point.

I have checked the output of the rectifier. The red line that feeds the CDI reads a 12 to15 according to RPM But it reverse polarity I have a very good meter. On On DCV+ it pulls the dial down past 0. I switch it to DC- it gives a 12 t0 15 VDC reading. At the battery it givesa 2 to 3 volt change at a constant RPM reading. When you raise the rpm it appears as the charging voltage drops.
I have done some more research.and found where it says it you disconnect the charging line to the battery and check the voltage across it that the power has to go somewhere. If not to the battery it will feed back through the diode and back to the charging system. That ruins the diode. I have know Idea what the previous owner did in his checking. I have a gut feeling that may be the problem. I found a whole front charging system and brain from a running bike that the motor bearings when out of for $200. That is my next step I would still like the VDC to check the stator also.
Ron in Arkansas You have all been so much help I can't thank you enough.

 

[rgpbeme]

Very Interisting,Reverse polarity

As some of you have read in my post on swapping CDI MPEM boxes because of reverse polarity charging let me get to the final chapter and it is odd

I was reading 12.5 to 14+ VDC neg. at the rectifier. I did this test with it unhooked. I tried 2 rectifiers and got the same reading. Unhooked the MPEM side showed 12.5+- VDC positive.

If you think I am crazy keep going. I had checked with dealers all over the area and none had heard of this (just my luck).

I had a brain f*rt and thought. Why am I getting voltage from the rectifier with nothing hooked to it? It is also a voltage regulator so with nothing feeding back what to charge why the sweep in out put voltage. It should be 0 volts I would think till it was hooked to something telling it to charge.

So what is before the rectifier looks to me like it is feed right from the stator
I changed the stator, put back the original MEPM and the other black box.

Ran down the battery trying to start it. (Forgot to turn the gas back on). Recharged the battery and started it right up. Checked the voltage with the rectifier unplugged (only a sec.) no voltage on the red. Checked the red to the MPEM 12.5 VDC+ Hooked them together and slid the meter probe under the insulator to the connection 13.5 VDC+ and it went up and down with the RPM Checked the battery it was 13.25 VDC. I have more checking to do but as of tonight the problem is gone. I am going to take a long look at the stator to see if something looks out of place
Thanks for the support:hurray:
Ron in Arkansas

 

[kustomkarl]

Well it sounds like it is either the gremlinsin the doo or it might be in the stator... electrical problems can make your pull your hair out sometimes...

 

[seadoosnipe]

Electrical system!

I've often read where members have wanted to put a different size motor or replace a different part to the electrical system becuause it was available. While many of the Seadoo's systems are comparable, they are, for the most part, different. It is recommended that you always replace an electrical part with the OEM part with the manafacturer's part number.

 

[rgpbeme]

The last straw

I got everything ready to go and went to the lake. It lasted about 16 min. and would not go above 3000 rpm It jumped to 4000 rpm for a second then back. I pulled it to shore and cleaned the plugs. It ran great for about 10 min. Then died. It would turn over ok just not start. I got it home and re checked the comp. 125- 0 . The top end was just rebuilt and the body shop where I got it said they spent $700 on it. Because of the elect. problem it was sold as is to me. I pulled the motor and looked One piston was dry and the pin that hold the piston on was missing one of the ring clamps. So the pin was sticking out one side of the piston. I hate it when that happens. So now I have to decide on throwing it away or starting over. What is the cheapest way to put pistons and sleeves in the 787 motor. I cannot afford to spend much more on something I have been on less that a hour.
So I do not know if the elect problem is fixed or not

 

[seadoosnipe]

Check your PM

I'm sending you a PM, please look at the top right hand side of your main page to receive my email. Thanks......Louis