01 GTX with carb bogs and dies at full throttle

[Wookie5]

Have just bought a 01 gtx, was told it runs perfectly. When we went it looked at he started it up quickly and he only ran it for a few seconds because of no water. So we figured should be good. When we got home and it had it hooked to our hose it would idle fine and when you would try to rev it up it would sputter and die.

We took the carbs off and rebuild them with genuine rebuild kit. Still nothing different. Could idle tell the tank ran out of gas but wouldn’t rev.

So we thought maybe getting some fuel but not enough fuel. Like the pump on the carbs was bad. So we tried a 2psi pulse pump from like a tractor. Still the same. So pump on carbs is good and hooked back up.

My uncle came over yesterday and listened to it, he called it a lean bog. But when you take the spark plugs out there soaked with gas.

All the fuel lines have already been changed from before me. We cleaned and replaced filters.

Don’t know if it could be something electrical. The ECU in the front of the pwc says it was changed in 2023, Maybe this is still a problem from then that know has had solved.

And does it make a difference on running in the river or a lake compared to a hose in my driveway?

Any help is appreciated, thanks

 

[Grim]

Yes , there is a small difference when running on the hose vs water, there is more drag when in the water so engine has to try just a little harder.

As for your issues a couple things come to mind. But first thing I would do is a compression test to make sure your motor is healthy. If they read lower than about 120 you are in need of a rebuild. Make sure you a have a good guage too. Make sure you hold the throttle all the way when testing too,

If that is good, I would do a test of your voltage regulator. Start the engine and put a multi meter on the battery, you should have mid/high 12 V reading maybe low 13V. Then "try" to rev it up , as best as possible in your situation. It should climb to mid to high 13V..maybe low 14V. Normally you should get it to 4500 RPM but that might not be capable for you. See if you can see a rise as best you can.

Other thing i would do is take the line that comes off the tank to your carb. Get a small bucket, add premix of gas and oil. Run the carb line to the bucket and see if you can rev it up, that will check your fuel system for issues. or tell you if it is carb related.

Also with the carbs, did you set you Pop off and do a leak test? Is your high speed and low speed screws set to factory.

Lastly, do you have an OEM MPEM (ECU) or is it aftermarket?

 

[Wookie5]

I don’t think that the fuel delivery is it because when I had that other pump on there we had it pump into bottle to check for that. So basically we know the fuel is getting too the carb.

We did not do a pop off test as we do not have a the right tools for that, might have to get them. And we did not change the high or low speed screws so I would I have to take the carb back off the make sure.

I am not sure if we have a OEM ECU. I just know it was changed. My dad did mention that he thought that it didn’t look like a factory one tho.

And I’ll have to check the voltage regulator. Is it in that electrical box in the back?

 

[Wookie5]

Now that I have looked up a picture of a OEM ECU the one we have is definitely a aftermarket one.

 

[Wookie5]

ECU picture , this link is the picture of the one we have.

 

[Grim]

Well that changes things...maybe. Aftermarket MPEMs are notorious for being flaky/weird and unreliable. But lets see if we an get it going anyway.
Testing the voltage reg happens at the battery, reread above explanation for more detail. I am not sure how your voltage reg is setup n the aftermarket units, I have a 98 GTX LTD and its integrated into the MPEM (boo). Maybe yours isn't.......if bad.

As far as the carb, pop off is really important for proper ops of the carb. I would suggest doing it. I made me a simple tester out of parts, not too hard or you can by a premade setup. Also, check the low and high while it is off.

Have you done a compression check? Working on a bad engine is an exercise in futility! Do you know how many hrs this machine has?

In case you don't now , there are manuals online, for free, that help with maintenance, get it and the parts breakdown manual too. There is a sticky thread on this site that shows the break down and rebuild of the carbs, look it over as well..

 

[Wookie5]

We have good compression.

We tested the regulator, the meter stayed at 12v the hole time. We got it to rev at about 3200 but anymore than that it will rev up for a second and die.

Did not get to pop off yet. But may have found the problem with that voltage.

 

[Grim]

Yeah if the meter didn't move when you started revving then the regulator/refictifer is bad. You will have to figure out where that is located on your aftermarket MPEM. Maybe the brand name's website will have info. You might be able to post it on here and see if anyone has changed it!

 

[Wookie5]

Alright, Thanks

 

[lavasioux]

We have good compression.

We tested the regulator, the meter stayed at 12v the hole time. We got it to rev at about 3200 but anymore than that it will rev up for a second and die.

Did not get to pop off yet. But may have found the problem with that voltage.

Agree- Bad voltage regulator for sure.

 

[Wookie5]

Would there be a chance it the magneto not giving voltage at all. Because My regulator is built into the MPEM and don’t want to spend 500 on a new without being 100% on the problem.

So basically, is there a way to test the magneto?

 

[Grim]

There is a check in the book to verify you are getting voltage from the stator. I believe using the yellow wires that connects to it, never hurts to try You can do that. I haven't heard of a ski running without the stator working to some degree but there is always today.