96 GTX Troubleshooting Ski

[Mettler]

Hey,

So, I try and keep this short but I am a bit baffled by this machine. We purchased this 96 GTX a month ago for a good price. It fired great out of the water, had to wait a week before putting it on the water and battery was weak and didn't want to start put a fresh battery in and it fired up right away again no issues. Started out on the water and it would never get out of plane, seemed sluggish and bog down. We checked all the common stuff like blockages and nothing. Brought it home to diagnose more on, checked compression on the cylinders and both good at 150 psi. Thought maybe a fuel issue, so changed the fuel filter and oil filter. Took it out again and it seems better at first hit 35 mph on the water and started to cut out, dropped down to 25 mph thought maybe I could keep on it and it would flush out the lines. As I was driving it kept cutting in and out a bit never higher than 35 mph, next it drop from 25 mph to 10 mph then died completely. After that I had no electrical no beep or gauge, thought maybe battery so on shoreline changed the battery and still had nothing. After getting it home again and diagnosing more it seems that my dess post is bad. Checked all the fuses in the front and back and they all good. Is there other things I should be looking at with this machine?

 

[POPPS]

Sounds like fuel delivery problems...run the inline to your carb directly from the pickup,,,to rule out the fuel selector, yours doesnot have a fuel filter, but water separator mesh filter,

 

[artr]

I agree with POPPS for the first part of your description. Does the ski still have the gray fuel lines? Do you know if the carbs were gone through by the previous owner and what was done?
The second part where you changed the battery and get no beeps or gauges, do the gauges light up and function for about 30 seconds if you just press the start button (no key on DESS post)? Although I am not 100% sure if a bad DESS would affect the gauges lighting up without the key, it would at least indicate that the MPEM is powered and responding to the start button input. I think there are DESS test procedures in the shop manual.

 

[Mettler]

I agree with POPPS for the first part of your description. Does the ski still have the gray fuel lines? Do you know if the carbs were gone through by the previous owner and what was done?
The second part where you changed the battery and get no beeps or gauges, do the gauges light up and function for about 30 seconds if you just press the start button (no key on DESS post)? Although I am not 100% sure if a bad DESS would affect the gauges lighting up without the key, it would at least indicate that the MPEM is powered and responding to the start button input. I think there are DESS test procedures in the shop manual.

Hey thanks for the responses, it does still have the grey fuel lines and I am in the process of replacing all of that. I dont know what at all had been done to these machines before i got them. As far as the electrical, my gauges dont even light up. When we did the oms test on both the key and dess post they both fail. So could all of this be cause by the dess post failing out or did some else short it out?

 

[artr]

Your DESS is probably failed and should be replaced. The key is probably fine and will work with a new post. If your DESS post read "open" with or without the key on it, then just pressing the start button should had lit up the gauges for 30 seconds. Make sure the battery is charged and test for 12V at the MPEM (the red wire with the purple stripe and a black wire at the MPEM). If that checks but still no gauges lit, then test the start/stop switch with an ohmmeter to see if it shorts out when pressed.
The gray lines are a likely cause of the cut outs. Pull the fuel supply line going to the magneto carb (front of engine) and see if the is green goo at the connection. If so, the internal passages as little internal filters are probably clogged. Carbs should be cleaned/rebuilt using genuine Mikuni parts and following the Carb rebuild sticky post at the beginning of the forum.

 

[soccerdad]

Do not run it again until the fuel lines are changed, AND the carbs are cleaned. You will kill it very quickly. These skis will not tolerate poor fuel delivery, even for a short amount of time.