97 GTX top speed issue

[rbach]

I have acquired a 97 GTX LTD which has a new motor in it. It seems to run fine but top speed is about 42 miles per hour. It comes out of the hole strong and seems to run perfect with the exception of the top speed. I have run along side my ski boat to check the speedometer and it is pretty accurate.
I am getting a low voltage warning flashing which I figured was likely a rectifier problem which may also be contributing to the top speed issue.
I bought a new rectifier but for some reason this ski just doesn't seem to have one.
There is only on control box up front and there is not rectifier anywhere near it.
Its possible this isn't really a 97, anyone have any ideas as to where the rectifier may be and what years didn't have a rectifier?
The ski can run for about a week without me having to recharge the battery, once last year after a really hard landing after a jump the low voltage warning went out but came back on again about an hour later which may also indicate a possible loose connection somewhere.
So if anyone has an idea as to:
1. Where might the rectifier be?
2. If the year is wrong and there isn't one, what else could I check for low voltage issue.
3. Could the voltage issue be a cause for the top speed issue and if not what other things should I be checking for.
Thanks for any help you guys can be.
Randy

 

[sanpan25]

Should go considerly much faster 50 + mph.

Does it feel like it is slipping when accelerating? If so wear ring and impellar are suspect.

Rectifier are in by or in the MPEM box. Do you have a volt meter? Take a battery reading before starting, while starting and when running. 12v when sitting, 12v or under when starting, higher reading running than when off.

 

[kustomkarl]

Here is a little more detailed info on the charging system.
When the engine is running, set your voltmeter for 20 VDC and put the leads on the correct terminal posts. With the engine running, you should be reading anywhere from 14.5 to 14.8 VDC. (typically this test is done at 5,000 rpms) This tells you your charging circuit is good. If the voltage is higher, the regulator is bad. If you’re not showing a charge and you've replaced the rectifier, you may want to do a test on the Magneto/stator/charging coil. If you’re not a premium member and you don't have access to a manual, this test will be hard to do without it. There are 2 fuses that protect the charging system. Check the 15 amp fuse in the MPEM and the 15 amp fuse between the solenoid and the MPEM.

The magneto and stator create un-regulated AC current. The "rectifier" converts that AC to DC current and the regulator maintains the current between 14 to 14.5 volts DC for the engines operation and charging circuit.
I hope this helps. Keep us posted on you progress.

Karl

 

[rbach]

Thanks for the info, to date I haven't changed the rectifier, I have a replacment but can't find it anywhere. I suspect that this model doesn't have a seperate one but is more likely built into the MPEM. I have checked the fuses in the MPEM and they are both good, I haven't done the voltage test to see if the fault really is the charging system or a faulty gauge.
The Seadoo is at the cabin which I can only get to on the weekends so I usually go armed for worst case scenario which is why I have the spare rectifier.
Seemed like an easy solution until you can't actually find a rectifier on this unit.
The voltage test will have to wait until the 1st of July to try it out.
If you have any insight as to where the rectifier may be hiding let me know.
Thansk

 

[rbach]

I figured it should be up in that range for speed, no sign or feeling of any slipping. In fact if it didn't have a speedometer and you weren't racing side by side with a similar machine you wouldn't really know there was a problem.
The guy who had the ski prior to me did make mention that he had replaced the impeller as well so I suppose it could be that the pitch on the impeller is not for top end speed but I would also think if the pitch was to small that it would be inclined to overrev which it doesn't at top speed.
Randy

 

[kustomkarl]

Yea...I'll check out the service manual...I'll have ananswer in 10 minutes.

You should add your model and year in your avitar like me, so its easier to find your information...plus you won't have to post it everytime on future problems. I post between 50 and 100 post a day...digging for your information from your first post slows me down...:rofl:

Karl

 

[kustomkarl]

The manual tells me the high voltage components are located in a rear electrical box (near the battery) It also says the regulator and rectifier is mounted ON the MPEM,(Multi Purpose Electronic Module). There are (2)15 amp fuses in the charging system. 1 is in the MPEM, and 1 between the solenoid and the MPEM.
I hope this information helps you out.

Karl

 

[rbach]

Thanks Karl, I've also tried to modify my Avatar but not sure it it worked. I'll keep trying.
Based on what you said about the location of the rectifier there is no way this can be a 97. The MPEM in this unit is the only thing up front and I've had it completely out and in my hand.
Is there a way to decode the Serial number to determine the year??
Randy