Why does my 2001 seadoo challenger 240 efi back fire?

I had the trottle body cleaned, the rectifires replaced, what else can i do??Why does my 2001 seadoo challenger 240 efi back fire?
I would try draining, cleaning, and replacing my fuel first. After that, you may have a bad plug or timing problem. I had this problem and it drove me nuts... until I exchanged my fuel.



Good luck,

JohnWhy does my 2001 seadoo challenger 240 efi back fire?
Plugs injector issues.Why does my 2001 seadoo challenger 240 efi back fire?
Several possible causes.



One is that the mixture is so far off that it does not explode at the right time, but instead just overheats parts.



Another is that the timing is so far off that it fires when a valve is open.

But I doubt it even has adjustable timing.



And another is that a valve could be burned or adjusted to badly that it is being held open.