96 GTX (787) Limited RPMs... Plz Help!!

[krp713]

My problem is my GTX will not rev above 4k rpm. Acts as if it is in a "limp mode" but have read the ski does not have limp mode. When the ski first gets in the water it will run GREAT for approx. a hour or so and then all of the sudden it will not get above 4k rpms. If I kill the motor and immediately restart it (i mean like 1 second later) it will rev up to about 6500 for about 10 seconds and then cut back to 4k. Kill it / restart & runs good for 10-20 seconds and it will continue to do this over and over all the way back to the boat ramp. If I let it sit for an hour or two I can ride for about 10 minutes before it cuts back to 4k. If it sits overnight I can run for another hour or so before it happens. I just don't understand why I can kill the engine and restart in 1 second later and it will run fine for 10 seconds or so. Electronics getting hot? Rave valves have been cleaned. Plug wires trimmed. Grey lines have been replaced and carbs are clean. What next? It has to be something electrical, but what?? Please help!!! Thanks in advance for those who take the time to reply.

 

[Bills86e]

The RECTIFIER may be going south. Check voltage at 5500 rpm's. If over 15vdc, its
bad. Bills86e

You may be getting water in rear E-box, shorting coil.
Go over the electrical harness, clean & di-electric grease each connection. Fuse
holders too.

 

[krp713]

thanks for the help.. rear box is nice and dry. Looked over connections already but will grease them as you suggested. Rectifiers are pretty cheap (compared to other problems it could have been) and that's not how my luck usually runs.... thanks again!! I'll post my results.

 

[SabrToothSqrl]

well

according to the shop manual, if it's not breaking 4k, check the battery voltage. it says if its too low it will limit the engine...

this is from the 01 manual, but i assume it's similar:

The MPEM has a special safety feature to limit
engine revolutions when the battery voltage is too
low.
For example, when the battery voltage reaches
8.9 volts for at least 30 seconds, engine revolutions
are limited to 4480 RPM.
When voltage reaches 7 volts for at least 30 seconds,
the engine is automatically shut off by the
MPEM.

 

[seadooya]

My problem is my GTX will not rev above 4k rpm. Acts as if it is in a "limp mode" but have read the ski does not have limp mode. When the ski first gets in the water it will run GREAT for approx. a hour or so and then all of the sudden it will not get above 4k rpms. If I kill the motor and immediately restart it (i mean like 1 second later) it will rev up to about 6500 for about 10 seconds and then cut back to 4k. Kill it / restart & runs good for 10-20 seconds and it will continue to do this over and over all the way back to the boat ramp. If I let it sit for an hour or two I can ride for about 10 minutes before it cuts back to 4k. If it sits overnight I can run for another hour or so before it happens. I just don't understand why I can kill the engine and restart in 1 second later and it will run fine for 10 seconds or so. Electronics getting hot? Rave valves have been cleaned. Plug wires trimmed. Grey lines have been replaced and carbs are clean. What next? It has to be something electrical, but what?? Please help!!! Thanks in advance for those who take the time to reply.

Unbelievably, i'v got same issue, with buddy's ski(96gtx). So far, the carbs are spotless, fule lines are done, water regulators' been replaced with known good one, raves cleaned, mpem has been switched, just switched out rectifier, with known good one....

I'll keep this thread going, cuz today, i'm switching mag cover/stator assy, and coil. Last possible electronic......just like yours, the ski will be a rocket, then outta nowhere, WHAm, 3500rpm, turn ski off, then whamo, back to 7k....it can stay there for 2-5 laps around lake, other times, it'll fall on face....i'm mad.

 

[seadooya]

alright bud, i switched stators...nut'n, went back into the grey box, and noticed that i didnt switch the igniter/cdi box..(located on underside of lid), well buddy has anutha ingniter, but cant bring to me til later, so i hooked up my 97spx(787) mpem, and all is good. So i'm think'n ur igniter is going south. Going to lake to test, will post later.

Switched coil, ALL WAS GOOD.

 

[seadooya]

Coil was the culprit.