94 GTX Low On Power

[wabash]

History. Ski has ran great since total rebuild 6 years ago. Last summer I noticed some slight cavitation on hard accel so I replaced the wear ring this spring with an OSD delrin ring. The old ring had some chips out of it. Also rebuild the pump and got a refurb impeller from SBT due to my original one having some pitting at the vane roots and some rock damage. First time out this summer and here's what I found

Symptoms. Ski feels like I'm pulling something. It normally pops right up on plane and builds revs quickly. Now it's slower to build revs and even though the top speed seems to be about the same the revs don't seem to be as high. There is almost no rpm increase from 3/4 throttle to wide open. Normally this ski would pop right up on plane and I could spin it and pop right back up. Now I can barely get it to spin out. I have another 94 GTX to compare to and it performs the same as this one used to. Engine doesn't miss. It sounds normal. Just feels like it's under a load like if I were towing something.

Simple checks I've done so far. Plugs are good color is good. Compression is 150 psi both cylinders which is what it always has been and my other GTX is as well using my gauge. Fuel strainer is clean. Fuel system was all gone through 6 yrs ago no gray lines. Although I don't pull the carbs every season I don't have reason to believe there's an issue. They're always stored properly with sta bil.

Story of the impeller. It's a refurb from SBT. When I got it I noticed the part number on it was different than the one I sent in which was stock. They told me it had been re pitched to the stock pitch. So I downloaded a pitch template and it did measure out to the stock pitch per the table on Seadoosource.


Looking for ideas.

 

[dieselndoo]

I'd get a couple neoprene seals, and swap pumps. See if problem follows

 

[wabash]

How much of a difference in pitch would it take to cause this?

 

[mikidymac]

I would also suspect a wrong pitch impeller. As dieselndoo said swap the entire pump from your other ski and see if it is better.
Another member here had the same issue with SBT impeller as they don't keep the factory part number so nobody even them can keep track of what pitch it actually is.

 

[wabash]

Yep that's the issue I had. They didn't send me my original back. I went round and round with them and they assured me it was correct. WRONG! Just got back from the lake again and I'm convinced it's the pitch. It throws a jet out the back like a hero but acts like the motor is in the wrong gear. Also I noticed at idle it seems to travel at a much higher speed. Took a perfectly good ski and ruined it. I'm so hot right now. SBT is now officially on my list of Jack Wads. And it's a fast growing list lately it seems that people can't do honest reliable business any more.

 

[wabash]

I'm going to skip past swapping pumps since I have to pull the suspect one anyway and prob need a correct impeller I'm just fast forwarding to that solution. We leave for Michigan next Thurs so I gotta have it go my by then. I don't want to spend my vacation with a dog ski the whole time.

 

[wabash]

SBTs getting an earful from me tomorrow.

 

[wabash]

Should I try re pitching?

 

[wabash]

The impeller I have is a 271000400 which crosses to a 94 - 96 Speedster right side. Stock part number is 271000280 which is a 15/21 pitch. I can't find what the stock pitch of the 271000400 is supposed to be the chart on seadoosource says ?? Using my printed off pitch templates I can see where it might be a 16/23. It is 15/21 but not in the last inch of each vane. The vanes take a turn to the greater towards the end both on the leading and trailing edges. I'm guessing this is where my problem is. Would that be enough pitch to make it feel doggy like it is?

 

[mikidymac]

I have had nothing but great service from SkatTrak for impeller refurbishment. IMPROS was also crap and took two attempts to fix one impeller.

SBT's service is about as good as their parts in my opinion. I don't waste my money there.

 

[wabash]

Well I was successful at repitching an impeller today. I tore the pump down and pitched it to what seemed closer to 15/21 towards the ends of the vanes took it back to the lake and it seems normal now. They had the trailing ends of the vanes tipped up the last half inch to inch. I moved the tips to what equated to about 3mm. Also tweaked at about 1 in in on the trailing angle and moved it about 1mm.

 

[wabash]

Went ahead and located a stock impeller and bought it. I had to tweak on this one way too much and I still don't think it's 100% correct. Bottom end still doesn't feel right. Nick and Jess at Westside Power Sports got one out to me today. Should've went to them first I won't make this mistake again. If I even think about buying from SBT again someone please shoot me.