95 SPX runs good for 10 minutes then barely runs/dies

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NoelNicklasson

NoelNicklasson

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Hey! so i just bought a Seadoo SPX with the 657x engine. It runs great for 10 minutes, has good idle starts easy etc.. but after i've been riding it for about 10 minutes, it starts bogging down and wants to die. it only runs on idle (barely) even dies sometimes. And does not want to start again until it's cold. I have cleaned the carbs, changed all the gray fuellines, and cleaned the fuel selector etc. I'm new to pwc's, what do you guys think can be the problem? i just can't wait to ride it and want to fix the problem asap!
 
How do plugs look? Had an issue similar to what you were describing and if you've refreshed the fuel system properly then I'd replace the sparkplugs as an added measure, sending us a picture of their condition too would be helpful.

Replacing the plugs (and caps since it used to foul plugs a good amount) fixed all my issues. Also cutting the plug wire back .5cm.

To take the caps off just remove the zipties and pull lightly while turning counterclockwise (left.) Installation is the opposite.

Assuming motor is healthy?
 
This info idea general, not 2 stroke or seadoo specific.
Could be a coil (pickup coil or spark plug coil). Sometimes coils work cold but then have issues when they warm up.
I'd say check for spark when it won't start, but it could be sparking still, just not every engine rpm. I suppose if you had an oscilloscope you could know for sure. Just switch those parts with a known good one and you'll know soon enough.
I've heard of cdi s doing the same thing when it gets hot, but it would be a well known issue if seadoo had this problem.
 
Try opening the gas cap when it quits, could be the vent creating a vacuum and starving for fuel. If that’s not it you are going to have to see if it’s loosing spark when it quits.
 
mikidymac said:
Try opening the gas cap when it quits, could be the vent creating a vacuum and starving for fuel. If that’s not it you are going to have to see if it’s loosing spark when it quits.
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i have tried opening it, but it does not help. I will check spark when it quits.
 
it does seem electrical, failing after it runs for a while, agreed, could be coil, cdi, stator, rule out charging system, (easiest) .
 
My 1999 SPX is doing the same thing. Had carbs rebuilt twice because i thought the shop didn’t do it right the first time so made them do it again, changed fuel lines, cleaned fuel selector, changed plugs and it’s still doing it. Shop told me it could be the ignition coil so took it out and took it to an auto electrician who tested it, they said it’s fine. Told the shop what the auto electrician said and they replied saying that when the auto electrician tests it that it’s not under load and so it might not show fault and that it could still be the coil. Just so tired of changing parts and spending money to not solve the problem. Please let me know if you manage to solve it and what the problem was
 
RTW said:
My 1999 SPX is doing the same thing. Had carbs rebuilt twice because i thought the shop didn’t do it right the first time so made them do it again, changed fuel lines, cleaned fuel selector, changed plugs and it’s still doing it. Shop told me it could be the ignition coil so took it out and took it to an auto electrician who tested it, they said it’s fine. Told the shop what the auto electrician said and they replied saying that when the auto electrician tests it that it’s not under load and so it might not show fault and that it could still be the coil. Just so tired of changing parts and spending money to not solve the problem. Please let me know if you manage to solve it and what the problem was
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Ignition coils can fail once they've come to temperature. I suggest spraying them with a light mist of water, they should still work fine with "dew" on them.
 
RTW said:
My 1999 SPX is doing the same thing. Had carbs rebuilt twice because i thought the shop didn’t do it right the first time so made them do it again, changed fuel lines, cleaned fuel selector, changed plugs and it’s still doing it. Shop told me it could be the ignition coil so took it out and took it to an auto electrician who tested it, they said it’s fine. Told the shop what the auto electrician said and they replied saying that when the auto electrician tests it that it’s not under load and so it might not show fault and that it could still be the coil. Just so tired of changing parts and spending money to not solve the problem. Please let me know if you manage to solve it and what the problem was
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i will change the ignition coil, i will post here when i get it working! :)
 
so my new coil came in the mail today. The spark right now is white/yellow ish. on both sides so im really hoping this will fix the problem. I will also change spark plugs.
 
so, i was testing it the other day, with the new ignition coil, it was now starting when it was warm, and it ran good for maybe 15 minutes. After 15 minutes it did not respond to gas, it had good idle, and started right up. but if you pulled the throttle it just bogged down. I tested it today also, i had been riding it for about 10 minutes when the lanyard came off because of big waves, it now does'nt want to start, it makes this weird sound every 2 seconds or so, sounds like it's backfiring (when im pressing the starter)
 
It may have ingested water? Remove the spark plugs, place spark plug wires on grounding posts and crank it over with the starter while watching for water shooting out of the plug holes.
 
i have thought that it might have ingested water, because there is quite a lot in the hull after ive been riding it. I will check that.
 
Here's An outside the box idea, check that you do not have an exhaust leak at the coupler, usually on the back hidden side, reach behind with your fingers, this is easy to do and easy to remove from your diagnostic equation. Next time it dies, pull the seat off, this gives the motor fresh air, to repeat the cycle.
 
I’m leaning toward an exhaust leak as well... The ski will run fine on initial start, and then begin to lose power as the bilge fills with exhaust fumes until it eventually can’t pull enough oxygen to run at all. Once it dies, it won’t restart until those fumes are displaced by fresh air again...
 
If it is an exhaust leak ensure your cooling system is functioning, otherwise your cyclicle symptoms will continue, and slowly you could score a piston.
 
I thought about exhaust leak too, and that it might fill the bilge with fumes causing it to suffocate. But i now have no spark at all. (It wont start even when cold) it's completely dead. I have changed the ignition coil. What should i try next and can i measure instead of buying new parts?
 
Sometimes the trigger pickup fails, the boat hits a wave and the pickup breaks, ( or gets partially dislodged), so these days we encoat our pickup with jet pump ultra black. check the resistance values of the pick up from the manual, I don't have them off hand. Make sure you pull out the front electrical plug, and that you do not have corrosion on the male pins ((use a mirror),, and just pry off the orange cap on the female end, no sense taking ohm values with incomplete connections.

Also for the same reason, taking stator values would be incorrect or off if that connection is partially corroded.

For the very same reason, ensure all your connections and grounds starting at the battery, is your easiest way to rule out issues from your diagnostic equation.
 
And have you done a load test on the battery, those dark plugs could be the result of weak spark(battery), and or low compression. Do a load test on the battery, and a compression test, on a fully charged battery.
 
The spark plugs are brand new (NGK br8es) and the battery is also brand new. And the compression is 150psi on both jugs. is 150 good? or should it be higher?
 
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