2002 Seadoo xp

[Scso130]

I have a 2002 Seadoo XP that acts like it wants to start but doesn’t and then back fires. Will the carb cause this?

 

[SabrToothSqrl]

was the engine ever apart? if the magneto was installed incorrectly, it would do that. Are the plug wires in correctly? They are specific to MAG/PTO. when did it last run?

 

[Scso130]

This was a new motor, i installed it but can’t get it to run. It acts like it wants to but doesn’t. Soon as I give it throttle; it back fires.

 

[SabrToothSqrl]

Was the magneto removed/adjusted?

 

[Scso130]

Not by me at all.

 

[SabrToothSqrl]

Well, you only need fuel/air/spark to run an engine. It's not suggested to, since it does not provide much lube for a 2 stroke, but you could try some starting fluid. If that kicks it over, then you have a fuel issue. Which could be carb related. If it doesn't start with that, then I'd look at a spark issue. There is a fuse or several in that e-box up front on those (It's been years since I sold mine). There's a black box the spark plug wires go to that controls them. Check the fuses in that guy, or pickup a spark plug tester like this:

https://www.harborfreight.com/in-line-spark-checker-63590.html
I'd also throw new plugs in it, if they are not new. NGKBR8ES if my memory is correct. (I used to be able to swap an entire 951 in like 2 hours)... but now I've become somewhat of a Mercruiser 350 expert for my new toy...

Do you have the factory manual for the 951?

Be careful opening that box in the front if you have to, the tabs like to break off and then it's not water tight. go slow and make sure you have all of them. I think there are 3-4 tabs. Position the seal correctly as well for reassembly. You get water in there and it's game over!

 

[Scso130]

I already replaced the computer, both plugs, the black electrical box in the front with the coils and plug wires, and the coil trigger. I’m like really lost on why it won’t start

 

[mikidymac]

How are the reeds?

 

[Scso130]

Should be good.

 

[Scso130]

It does the exact same thing if I switch the plug wires around. Thinking I might have the wrong ones plugged to the wrong spark plug.

 

[mikidymac]

Shouldn’t matter as they both spark at the same time, it’s a wasted spark system. I think only the DI and RFI are cylinder specific.

 

[Scso130]

Ok. So either carbs are bad and letting to much air into the cylinders or it’s out of time

 

[Mraw]

You sure the reeds are good?

 

[Scso130]

It’s a new motor. Should be , never been started that I know of, how would one check the reeds?

 

[mikidymac]

Pull the reed cages and check if you aren’t 100% sure. Not much will cause a backfire on a 2-stroke.

 

[SabrToothSqrl]

Shouldn’t matter as they both spark at the same time, it’s a wasted spark system. I think only the DI and RFI are cylinder specific.

This is not a wasted spark system. the 98 951 was. 99-02 was not.

 

[Scso130]

So the timing is probably off since it doesn’t change when I change the wires around. ?

 

[SabrToothSqrl]

Timing is not adjustable. The MPEM manages it. Have you verified spark? You'd have to pull the carbs to check the reeds, they are under the carb to block adapters. Even with bad reeds, it would at least fire.

I'm still leaning to either the magneto being the wrong part, or installed wrong, or the sensor not working correctly. Very easy to mis-install. Same thing happened to me a few years ago, I'd crank and crank and every now and then it would fire, but then it would back fire so bad it collapsed the rubber hose in the exhaust. Turned out to be I used a 98 magneto vs. a 99+.

On the XP you can actually swap the magneto without removing the pipe or engine... support the engine from above, remove oil pump, remove front mount. remove 20 10mm bolts on mangeto cover. Don't forget the plastic oil pump drive adapter either when you reinstall! I had to redo everything when I found that in the hull!

you can post a video?

 

[Scso130]

Yea, I’ll video it and post it. Then you’ll have a better idea of what it’s doing. Thank you very much.