98 seadoo xp limited 951 issue!

[rubioz46]

i have a 98 seadoo xp limited that has been acting up lately. When i crank it it starts reving up by itself for no reason and no the trottle isnt stuck. ive tried two sets of carbs and they do the same thing. the weird thing is it doesnt do this in the water but when im full throttle it sounds like the timing is to far advanced. Sounds kinda like a valve clatter. Has anyone had this problem before or know what it is?

[Technical Support]

Re: 98 seadoo xp limited 951 issue!

Its running to lean from carbs or you have an air leak from the crankcase or intake.

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

well to lean is out of the question. 1 i used two sets of carbs one was off a running ski. 2 i dont understand y it would rev if its running lean. but a air leak is very possible i took the covers off where the reed pedals are and the covers and the reeds looked good. any ideas here else the leak could be?

[dsolie]

Re: 98 seadoo xp limited 951 issue!

Did you do any work prior to this happening, or did it just start on it's own?

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

All of a sudden. I don't understand the whole rev by itself out the water but idle perfect in the water. I understand its under a load but that's still weird. The "valve clatter" comes and goes at full speed and it will jump from like 58 to 65

[dsolie]

Re: 98 seadoo xp limited 951 issue!

Valve clatter??!! There are no valves to clatter, unless you are talking about the RAVES, and those do NOT clatter, ever.

Try opening up your lows, just a smidge. See if that calms her down.

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

I understand how the raves work. I mess with small block 350s a lot and I'm just comparing to the noise. It sounds like the timing advances to far for some reason. I'm gunna try swapping the computer and see if this helps because at a idle I don't see y a motor would rev up if more gas isn't bein dumped in the motor.

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

Think about what ur saying ur telling me to apply more gas when my motor is already tryin to rev up by itself out the water. Haha sounds like u want my ski to go kaboom!

[dsolie]

Re: 98 seadoo xp limited 951 issue!

Seriously? If that's your take on it, then your ski is bound for failure.

Do you KNOW why your ski is free-reving? It's called being LEAN. Due to lack of fuel, or an air-leak. Opening up the low speed adjusters is not the same as opening the throttle. Take my advise or not, but swapping the computer doesn't control the fuel curve OR the throttle. Just the ignition timing, which has nothing to do with your issue.

When you move the distributor cap on your 350's, do you redline? NO. Because it doesn't control that system. But, when you play with the jetting in the carbs, tuning it, you optimize your throttle response.

Good luck!

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

I don't understand y I took one set of carbs off a perfectly running ski and stuck them on mine and same thing. Do u think if I backed my ski into the water and sprayed something on and around the motor I could find the air leak?

[ashpapi]

Re: 98 seadoo xp limited 951 issue!

without hesitation, I tell you that the 951 motor is the TOUCHIEST for carb setting. PLEASE listen to dsolie, I am staying out of it other than to say that I would have a tough time remembering when a 951 came in that did NOT run off if the carb was not at a PRECISE setting. And I mean a precise setting for that carb only, no rule of thumb. I was told you can look for a leak (bubbles) with a liquid, that is always a possibility. but try to experiment with those carb settings per dsolies suggestions, I defer to his expertise.

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

Aight ill try and update tomo.

[Technical Support]

Re: 98 seadoo xp limited 951 issue!

A lean condition is caused by lack of fuel or an air leak, don’t try to compare 2 stroke symptoms to 4 stroke symptoms they are very different. If both sets of carbs act the same way on the engine then it is most likely an air leak around the case or a crank seal gone bad.

[rubioz46]

Re: 98 seadoo xp limited 951 issue!

I found this posted on another website. Its pretty forward and points out just what to check for thanks anyways guys. That engine is on a run-a-way path.

1. Most common reason is out of the water and the idle set just 100 to 200 rpm too high. The confusing part to a 947 newby is that all other 2 stroke Sea doo engine models are set to 3000 rpm out of the water, but a 947 idles perfectly in the water when you set the idle speed at 27-2800 out of the water.

2. Allowing the head to get too hot becuasue it is running without water going through the motor when on the trailer.

3. And some of these next reasons could be a toss up in order, Replacing the carbs onto the engine for whatever reason and setting up the throttle cable adjustment too tight at the carb cable bracket, leaving the throttle plates slightly cracked open.

4. Clogged or partially clogged low speed jets.

5. Low speed adjusters are set too far in, not allowing enough fuel to pass at idle speed.

6. Water in the gas tank that ends up inside the carbs blocking fuel flow through the jets.

7. A poor job of keeping the carb base gaskets aligned when replacing the carbs onto the manifolds equals an air leak.

8. A pin hole or split in the plastic tubing that connects the engine case pressure fitting to the check valve in the rave valve pressure supply line, or a broken check valve in that same line. This allows air to go into the engine during up strokes, leaning out the mixture.

9. One stuck needle valve that will not open.

10. Rust inside the carbs, see #6.

11. A pin hole in the fuel pump pluse line.

[str8g]

Re: 98 seadoo xp limited 951 issue!

I would agree it sounds like a lean type condition. Also take what Dan has to say seriously. I just went through a lean situation on my 99 xp and ended up having to go through the expense of a top end rebuild. I had a similar situation as you are discribing and it was due to a pin hole in the fuel pump diaphram. The fact that you describe the same problem with both sets of carbs installed would lead me to think of starting with the fuel system before the carbs and rule that out. Lean type situations can be created from restriction of fuel ( plugged fuel selector, or fuel filter- before carbs) or another lean condition air leak with in the fuel system before the carbs (fuel filter O ring). not to mention low fuel pressure. The motor pulls the same amount of vacuum when running correctly and its up to the fuel system to feed the correct amount of fuel. If the fuel system is feeding the correct amount of fuel and there is a bad crank seal (air leak) then it is allowing even more air to be pulled in and that can create a lean situation. Follow Dan's advise for that situation. I would rule out the stuff tank to the motor first before I moved to something else. I started to develop my lean situation in my 99 and did compression tests each time I tested and unfortunatley by the time the issue was discovered and resolved I lost 20psi on the front cylinder and it ended up costing me. I was told that the chattering can be from the balancer gear teeth on a rough running engine??? Not sure about that one though???