GTX 951cc idle and running issues

[gtx2000]

Hi just took out my seadoo today after putting it all back together. Just had a rebuild top end and barrels etc by someone else.

Started well and idled and ran well for about 20 mins pretty smoothly and all seemed good. Was running it in slowly and didn't rev it past 50%. However after a while it stated running rough at low revs. Splutting a bit and then problem slowly got worse. Then after stopping in the middle of the river and tried to restart it wouldn't fire and just cranked and spluttered. Got it going by holding throttle flat and cranking it. It fired and ran rough. Managed to head back to the boat ramp and on the way back it wouldn't idle but would surge. Had to hold the throttle almost flat stick and then back off as the power kicked in just to get back.

Seemed like a fuel starvation issue or running on 1 cylinder at low speed and 2 cylinders at higher revs?

Has old fuel and oil in it so I should probably start there by replacing that. Got back on the trailer and it still won't idle but runs at half stick and only under revs. Likely needs carby tune and fuel system clean out. But any tips welcome or any similar experiences - I'm keen to hear. Thanks in advance.

 

[mikidymac]

Why would you run a new top end on old fuel and dirty carbs is beyond me.

Rebuild carbs with only genuine Mikuni parts. Replace any gray fuel lines with standard automotive. Replace fuel valve and clean fuel strainer and replace it’s o-ring. Make sure your accelerator pump is squirting.
I would check compression to make sure you didn’t destroy your new top end from running lean.

 

[gtx2000]

I just started it up again after sitting for a week.
It runs ok and idles now on the trailer. So Im guessing it could be something to do with when it gets warm. Not sure where the accelerator pump is so will look that up.

 

[gtx2000]

Didnt want to take out all the exhaust and rebuild the carbs yet. That is a big job. The carbs where fully cleaned with carb cleaner prior to installation before. I need to put new plugs in it too.

 

[mikidymac]

Carb cleaner won’t do much. You actually need to replace the rubber parts and needle and seats to do it correctly.

Also carbs can be removed without touching the pipe.

 

[gtx2000]

Ok thanks i will check that out and see how hard it is to remove

 

[CrocDundee]

We have two 97 XP 800 that are mostly running fine. In addition we are rebuilding two 951s, and these seem to be a little more challenging.

Getting the first 951 running correct through the full throttle range took some time. The folk on here and all their hints are excellent. My last run out on the 951 98 XP was great after a careful carburettor rebuild, although it had a rather unfortunate ending due to a wee fuel leak from the main separator/filter. Most post the video sometime.

Back to your machine. I am supporting the suggestion of care on the carb rebuild. They come off easy enough without moving the exhaust and you get good at finding the 4 hex bolts. I am sure Mikuni parts would be best, but in the UK it is possible to get other parts more easily and cheaper. Also reseating the needle valves is possible with a cotton bud, toothpaste and a drill. Carb cleaner through all the ports seems worthwhile. I replace any carb parts that are malformed or not functioning correctly. Particular care on the mylar flap valve, that it is working well.

Then following all the guidance here and in the manual about pop-off pressure and especially making sure there are good fuel lines and no air leaks in or fuel leaks out. I balanced the pop-off pressure as close as possible to each other (within a few PSI, in my case about 25, I think). Glue the carb manifold gaskets on to one surface to enabled the carbs to be refitted. Reset the low and high needles at the published settings. Then reinstall.

Final check on the fuel lines that both the inlet air valve and the outlet over-pressure valve (about 4 PSI, I think) are operating as required.

Good luck that you get it running well before my four previous fiddling and tests. When it is right, you sure know cause the ski tears around.

 

[gtx2000]

Just to follow up took it to the ski shop. Full clean out of carbies and numerous bits in the carbies replaced. New plugs and full tune. Test run tomorrow.