1997 GTX impeller issues

[Daytona20]

I am getting my GTX ready for the season and I am wanting to ask a few questions. Hopefully some of the members here can help me.

I bought my 1997GTX in spring 2009. When I bought it I could never get the seadoo to hit 7000 rpm when running flat out. The most I could get out of it is about 6750 rpm. When i was inspecting it this year and getting ready for the season I found a 1.5 inch crack in the hose connecting the tuned pipe to the waterbox. I can tell that it is leaking exhaust because of the black spray on the waterbox that is right where the crack is. It does not appear to be leaking water. would a crack in the exaust hose cause the engine to not develop full rpm's? I am planning to check the water regulator as well because i know the water regulator can cause this problem as well. Compressions tests at 142 and 148 for both cylinders and has not changed.

My second question is about a loss of top end speed. I lost about 4 mph over the season last year. when i pulled the nozzle today I measured the wear ring clearance at 25 thousandths with no gouging or missing chunks evident. the attached picture shows what the trailing edges look like on all 3 blades of the impeller the leading edges show minor wear. Is this normal or is this a sign to get the impeller replaced? My seadoo also has a lack of power from a standstill. I have seen a 97 GTI with an 85 hosepower engine get a better holeshot than I can with my GTX.

Any help or suggestions would be appreciated

 

[Bills86e]

Yes, you need to fix exhaust leak. WR...If it leaks internally water will be injected at wot and that added backpressure takes away HP from haveing to push out the water that is NOT supposed to be in there.

Clean your Raves

Jetpump clear is .008 as good, .040 is cavitating BAD
You do not need a new impellor, the wear-ring is supposed to wear, not prop. (cheaper). .025 may be questionable, but IMO is an issue.

Is Fuel delivery updated? Are you up on maintenance?

 

[Dr Honda]

As said above... fix the hose, and clean your raves.

Also... yes, your wear ring is in spec. but the bigger the gap, the more pressure you will loose, so if you are looking for every last bit of perfomance... then replace it. While you are in there... replace the impeller with a skat track swirl. That will give you the best hole-shot.


And fianlly... you probably won't see 7000 rpm. Yes, your red-line is 7200... but unless your engine is running perfect, it won't get there. Hows your compression? How old is the engine?

 

[Daytona20]

I have the exhaust hose on order and will be replacing once i get it.

Pulled the water regulator and examined for signs of wear on the needle. cracked or damaged bellows. everything looks good.

The first thing I did when I bought the seadoo was to clean the rave valves. Examined near the end of the season last year and they did not need cleaning. Pulled them and cleaned them anyway a couple of days ago.

Replaced the plugs at 10 hour intervals irregardless of condition. If anything they may be burning just on the rich side of good according to seadoosnipes plug guide. i am going to recheck them along with the rave valve condition this season and make any necessary adjustments to carbs if required.

replaced all grey fuel lines last season. replaced carb fliters even though there was absolutely no green gunk in them. I did not see a reason to rebuild carbs.

I pulled the jet pump this evening and the leading edges are showing a little bit of impact damage or possibly cavitation damage. I was launching from an area in front of our cottage that did have a fair bit of weed buildup last year. The wear ring has very tiny little groves worn into it so since i am pulling everything apart I might just as well replace the wear ring.

My main concern was with the attached picture of the impeller and the wear pattern I am seeing on the trailing edge. the trailing edge does not form a straight line but a slightly v shaped edge and I was wondering if that was normal on the impeller. An abnormal impeller trailing edge could disrupt water flow coming out the back so i am told.

I am also planning on pulling the driveshaft and replacing the carbon seal and associated parts. the carbon seal seems to sit about an eighth of an inch to one side of the driveshaft mating plate. The rubber boot is in good shape. I has assumed that there was a bearing where the driveshaft goes through the hull but was surprised to see that there was no bearing. When i look at the driveshaft and the engine it seems like the engine is not sitting on the centerline along the hull. if I were to loosen the engine mounts and slide the engine about half and inch to the right which would make the carbon seal sit perfectly on the driveshaft mating surface. How critical is it to have the engine sitting perfectly on the centerline of the hull? I am assuming it is pretty critical.

 

[Dr Honda]

I have the exhaust hose on order and will be replacing once i get it.

Pulled the water regulator and examined for signs of wear on the needle. cracked or damaged bellows. everything looks good.

The first thing I did when I bought the seadoo was to clean the rave valves. Examined near the end of the season last year and they did not need cleaning. Pulled them and cleaned them anyway a couple of days ago.

Replaced the plugs at 10 hour intervals irregardless of condition. If anything they may be burning just on the rich side of good according to seadoosnipes plug guide. i am going to recheck them along with the rave valve condition this season and make any necessary adjustments to carbs if required.

replaced all grey fuel lines last season. replaced carb fliters even though there was absolutely no green gunk in them. I did not see a reason to rebuild carbs.

I pulled the jet pump this evening and the leading edges are showing a little bit of impact damage or possibly cavitation damage. I was launching from an area in front of our cottage that did have a fair bit of weed buildup last year. The wear ring has very tiny little groves worn into it so since i am pulling everything apart I might just as well replace the wear ring.

My main concern was with the attached picture of the impeller and the wear pattern I am seeing on the trailing edge. the trailing edge does not form a straight line but a slightly v shaped edge and I was wondering if that was normal on the impeller. An abnormal impeller trailing edge could disrupt water flow coming out the back so i am told.

I am also planning on pulling the driveshaft and replacing the carbon seal and associated parts. the carbon seal seems to sit about an eighth of an inch to one side of the driveshaft mating plate. The rubber boot is in good shape. I has assumed that there was a bearing where the driveshaft goes through the hull but was surprised to see that there was no bearing. When i look at the driveshaft and the engine it seems like the engine is not sitting on the centerline along the hull. if I were to loosen the engine mounts and slide the engine about half and inch to the right which would make the carbon seal sit perfectly on the driveshaft mating surface. How critical is it to have the engine sitting perfectly on the centerline of the hull? I am assuming it is pretty critical.

It's normal for the carbon seal to be sitting off to one side. The hole in the center is bigger than the drive shaft.

DO NOT MOVE YOUR ENGINE!!!!!!!!

The engine is aligned to the pump. since there is no way for your drive shaft to allow a miss alignment... if you move your engine, you may bend the driveshaft, or you will eat the splines in the PTO or the impeller.... or... you could kill the pump bearings.