Is this a rectifier issue?

[Sportster-2001-951C-Stock]

Well I think we are getting closer. So this morning I checked the battery. 12.8 volts. Unplugged power from computer and checked voltage at front of the jet ski. Only 4 volts. I then jumped it at the solenoid and it started right up. My thinking is there is a bad wire somewhere after the solenoid and before the MPEM.

Hi, I would agree there is probably a bad wire or connection somewhere between the solenoid and MPEM.

This is a process of elimination, so if you jump the two large posts on the solenoid and the starter cranks the engine, it rules out the battery cables and starter.

If you measure the voltage on the red (output) terminal of the regulator/rectifier, and measure some value less than the battery voltage, it confirms there is an lose or corroded wire/connection somewhere between the regulator output and the battery positive terminal.

Once confirmed, then it's a process of working back towards the battery from there, until the voltage is found, then narrowing it down from there.

So yes, we suspect a lose connection or corroded wire somewhere but there are two sides to the electrical system, the positive side and the ground side, so we have to check both of these. Most of the wire, and the fuses, are in the positive side of the wiring harness, so most likely that's were the problem is, however, the grounds are often low in the bilge where they connect to the engine block, thus can corrode due to the wet/hostile conditions.

I'm quite certain the problem is a simple one and once located should be an easy fix, we have no indication of any major parts being defective based on the info collected so far.

So, please find the red wire on the rectifier/regulator and measure the voltage from there to the battery negative terminal. If 12V, then also measure from red wire to engine block, this should also be 12V.

 

[quadchris8390]

I haven't found a way to measure yet before it gets to the MPEM in the front. When I got the 4 volt measurement, it was the wires going from the MPEM to the rectifier. Is it possible that I am losing power through the MPEM? In which case would be a bad thing. I cant see where to take a measurement right at the MPEM before it plugs in.

 

[Coastiejoe]

I haven't found a way to measure yet before it gets to the MPEM in the front. When I got the 4 volt measurement, it was the wires going from the MPEM to the rectifier. Is it possible that I am losing power through the MPEM? In which case would be a bad thing. I cant see where to take a measurement right at the MPEM before it plugs in.

There is a main wire that feeds the MPEM. In all my reading thus far, it is a red wire on the battery side of the solenoid as it is an always hot wire. Check that connection and wire well. Follow it to the MPEM. Look for a cut in the wire, measure the voltage at both ends, see if there is a drop, ect ect...

 

[Sportster-2001-951C-Stock]

I haven't found a way to measure yet before it gets to the MPEM in the front. When I got the 4 volt measurement, it was the wires going from the MPEM to the rectifier. Is it possible that I am losing power through the MPEM? In which case would be a bad thing. I cant see where to take a measurement right at the MPEM before it plugs in.

Possible, but not probable, IMO, until you confirm power is entering but not leaving MPEM.

Let Coastie help you going forward, too many cooks can spoil the broth.

 

[Coastiejoe]

Possible, but not probable, IMO, until you confirm power is entering but not leaving MPEM.

Let Coastie help you going forward, too many cooks can spoil the broth.

Don't leave me hanging,,,,
I have very good general now ledge and a good grasp of how and why things work. It is specific knowledge that I still lack in regards to all of the nooks and crannies of Seados..

So please, your advice is welcome and encouraged...

 

[Sportster-2001-951C-Stock]

Don't leave me hanging,,,,
I have very good general now ledge and a good grasp of how and why things work. It is specific knowledge that I still lack in regards to all of the nooks and crannies of Seados..

So please, your advice is welcome and encouraged...

Specific knowledge - Me too man, I wouldn't know the difference between a '96 model and a '97 model, I can only guess they're the same. Unfortunately, I don't have the schematic for a '97, so I don't want to stand in the way of steering towards the specific problem due to my having to do some blind navigation, LOL!

Although lack of detail rarely is an excuse for me to avoid an attempt, I don't want to get in the way......

So anyway, I see a 5Amp fuse in the drawing that is on the MPEM, check to make sure there's 12v on that thing, it's the power feed to the MPEM. There's a 15Amp in there as well. Looks like those are fed 12v by the Red/Blue wire going to the MPEM. That wire connects to another, which is Red/Purple, that comes from the 15Amp fuse in the rear e-box where the ignition coil is.

So, if no power at red wire of regulator, and no power at 15A or 5A fuse of MPEM, then find Red/Blue wire which feeds power to MPEM and follow it back to where the color changes to Red/Purple and check both sides of that connection. If no power there, then there is no power coming out of rear ebox on the Red/Purple wire.

Or, you could go right to the rear e-box and check the Red/Purple wire to see if there's power there, and from there, work towards the MPEM to find where the power interruption occurs.

 

[quadchris8390]

I have 12 volts on the fuses at the MPEM. It was a pain to get a reading. I am only getting about 4 volts out of the red wire on the rectifier.

 

[quadchris8390]

its definitely not the rectifier either. Took the one out of my good jetski and tried it. Same thing. No power.

 

[Sportster-2001-951C-Stock]

I have 12 volts on the fuses at the MPEM. It was a pain to get a reading.

A PITA:
Yep sorry, I could have made life easier if I'd mentioned the blade type fuses have small openings on their top corners for this purpose (access holes for in-circuit testing), so checking both corners to a reference ground will reveal if the fuse is blown, the voltage should be the same on both, not 12v on one and 0v on the other:

"Locate the small holes on each end of the blade-type fuses; those holes give you access to the blades inside the fuse. Insert the pointed tip of the red test lead first in one hole and then in the other. If you read 12-volts to ground on one end but not the other, the fuse is blown and needs to be replaced."

http://www.ehow.com/how_5783313_use-voltmeter-test-fuse-block.html

I have 12 volts on the fuses at the MPEM.

Okay, good. I hope on both top corners, meaning the fuses are not blown(electrically open).

We're making progress!

So just to reconfirm my understanding, the MPEM has power on the 5 Amp and 15Amp fuses but MPEM still appears dead, no signs of life(such as gauges or lanyard buzzer beeps) and if you jump the two large terminals on the starter solenoid, the starter will crank the engine.

I am only getting about 4 volts out of the red wire on the rectifier.

Okay, this is interesting. It seems if I'm looking at the correct schematic, the power coming from the regulator (normally while the engine is running, the regulator provides the electric power at ~13,8 volts which flows toward and recharges the battery) must flow through the 15A fuse in the MPEM on it's path to the battery.

BTW, if the ski engine is not running then the voltage (12V) comes from the battery, through the MPEM 15Amp fuse, and is present at the regulator output red wire. (assuming my schematic is correct for your ski, of course). Once the engine starts, the regulator puts out ~13.8 volts and current flows towards the battery to recharge it. Higher voltage flows towards lower voltage, like water flows down hill.

Okay, so I'll get back to you after this short commercial message.........(insert commercial here)

 

[quadchris8390]

That is correct. No signs of life. No beep, nothing. I can jump it from the solenoid. I was reading over 12v on the fuses. I had to use a wire to get the reading. Didn't see the holes on the fuses.

 

[Sportster-2001-951C-Stock]

It's beginning to look like there's something awry in the MPEM but I'm still unwilling to commit to that. First, tell me where you have been placing your negative voltmeter lead during your testing? On an unpainted screw of the engine, the negative battery terminal, or maybe have you been moving it around from place to place? I just need to confirm this to keep myself synchronized....

 

[quadchris8390]

I have been moving it around from place to place. Can't reach the engine from the front of the jet ski with these leads on my multimeter.

 

[Sportster-2001-951C-Stock]

That is correct. No signs of life. No beep, nothing. I can jump it from the solenoid. I was reading over 12v on the fuses. I had to use a wire to get the reading. Didn't see the holes on the fuses.

Yes, the voltage measurement should ideally be 12.5 or slightly greater, if battery voltage at the battery terminal drops below 12.5v, it indicates the battery might need charging. The MPEM will stop working if the battery voltage lower than 10v.

 

[quadchris8390]

Let me ask you this. I have 2 of the exact same jet skis. How hard would it be to take the MPEM out of the working one and put it in this one? Looks like there are just a few harnesses to unplug. That would tell us if it is in fact the MPEM.

 

[Sportster-2001-951C-Stock]

I have been moving it around from place to place. Can't reach the engine from the front of the jet ski with these leads on my multimeter.

That's acceptable as long as it's always the same electrical ground potential. The measurement I'm most interested in at the moment is the red wire on the rectifier, 4v indicates there is a problem between the rectifier and the connection at the MPEM, but every measurement needs to be made from the same electrical ground potential if possible, an unpainted screw on the engine is where I am, in my mind.

Does it look like a difficult task to remove the MPEM?

I'm beginning to think though, something's not right with the MPEM but the only way I can commit to that is if the regulator red wire measurement reference is to the engine block and the 15A fuse in the MPEM is confirmed good. It appears power is reaching the MPEM, but the MPEM also has to have ground else a current path doesn't exist.

Are there only 2 fuses in the MPEM, or are there 3? I see a 3rd fuse next to a relay and it's a 5A fuse, but it provides power to the CDI ignition and so would not cause our symptom of no gauge action.

 

[Sportster-2001-951C-Stock]

Let me ask you this. I have 2 of the exact same jet skis. How hard would it be to take the MPEM out of the working one and put it in this one? Looks like there are just a few harnesses to unplug. That would tell us if it is in fact the MPEM.

I'm beginning to think this might be a good idea, b/c there is power in the MPEM yet the ski is dead. The only other thing that I can think of other than a problem inside the MPEM is, one of the grounds somewhere may have a bad connection, that would also cause the MPEM not to work, but since there's only 4v at the regulator it points a crooked finger directly towards a lose connection inside the MPEM.

 

[Coastiejoe]

Let me ask you this. I have 2 of the exact same jet skis. How hard would it be to take the MPEM out of the working one and put it in this one? Looks like there are just a few harnesses to unplug. That would tell us if it is in fact the MPEM.

The MPEM is testable. We have members that can do so.

If it were me, I'd swap the MPEMs. This would tell you a Tom of information.

If it works, the MPEM or a connection at the MPEM was bad.

Does not work, still looking for a wire issue.

 

[quadchris8390]

I really do appreciate the help you guys have given. More than you can imagine. I am not the most technical person in the world and feel I know so much more because of you guys.

So. I took the MPEM out of the good ski and put it in the bad one. Did not work. I put the (what I thought was bad) MPEM in the good ski. Started right up. I am thinking ground wire somewhere. From what I can see, everything looks tight and no nicks. You had mentioned grounding wires on the engine. Any idea from schematics where this would be? I am not seeing them.

 

[Strizzo]

the ground for the entire electrical system comes from the battery negative to one of the ears on the starter, the electrical system gets its ground from the motor via this wire, so if there is good ground to the motor (there is since it turns over when you jump the solenoid) you should look for bad ground connections between the rest of the electrical system and the motor.

 

[Strizzo]

View attachment 97 GSX wiring diagram.PDF

Here is the 97 GSX wiring diagram i printed out and taped together. check pins 2, 16, and 17 in connector #2 for continuity with ground to the engine, and check for voltage at pin 18 and 19 in the same connector. my guess is you will find at least one of them has a bad connection or low voltage.

EDIT: fixed diagram so that its right side up, the rotation wasn't sticking.

 

[Coastiejoe]

You have done well with all that you have done in regards to testing and what not.

At this point I would run a ground from the block or the battery to the MPEM.

Simply eliminate the potential of a bad wire or poor connection. I'm flying again so I can't confirm which is the ground wire.

I'm sure someone has access to the schematic and will help though.

 

[Sportster-2001-951C-Stock]

Nice move Strizzo, the known-correct schematic is ALWAYS a big plus!

And, it's completely different from the '96 in the way it's drawn(electrically quite similar), this is gonna help a bunch!

Connector 2: pin 2, pin 16, pin 17, pin 18, pin 19 - All of these are power in and grounds, time to fire up the voltmeter and go to town! You can back probe these without removing the connector from the MPEM by using a straight pin, shove the pi into the back of the connector plug next to the wire and in till it stops and makes contact with the pin, or, you can pull the connector off and probe it from the pins on the open side of the connector.

Many times, the formal grounds for the MPEM are smaller diameter black wires running from the MPEM to the engine block and placed under a screw head on the block.

Now that we have a decent schematic, we can find the problem.

 

[Coastiejoe]

Good info Srtizzo,,,

Should be able to isolate it out I would think.

 

[Sportster-2001-951C-Stock]

3-26 Okay, so power comes into the MPEM on connector 3, pin 26, it's a red/purple wire. If there's power here, there should also be power at 2-26, (connector 2 pin 26), which is the red wire from the regulator/rectifier.

This ski has a DESS as well, so swapping the MPEM requires the DESS lanyard to swap as well, unless they were both programmed at some time for interchangeability.

Lots of stuff to check.

 

[Strizzo]

Good info Srtizzo,,,

Should be able to isolate it out I would think.

3-26 Okay, so power comes into the MPEM on connector 3, pin 26, it's a red/purple wire. If there's power here, there should also be power at 2-26, (connector 2 pin 26), which is the red wire from the regulator/rectifier.

This ski has a DESS as well, so swapping the MPEM requires the DESS lanyard to swap as well, unless they were both programmed at some time for interchangeability.

Lots of stuff to check.

I replaced the uploaded .PDF with one that was rotated right side up. you can re-download and make things a lot easier to read.