Re: yamaha waverunner vxr 1992 missing then quit running and now wont start
Pull the plugs and see what condition the motor is burning in. Are the plugs new? If not, for as cheap as they are, go ahead and buy new ones, install, and get it to run again if you can. After that, pull them again immediately afterwards and check the burning condition. You should be able to tell if it's burning too much oil and fouling plugs.
I just bought a 97 Yam GP760 that basically did the same thing (without dying) on my maiden voyage. I bought new plugs before the trip and stuck them in the storage compartment just in case. Good thing I did, because once I pulled the old ones out (which didn't show indication of malfunction) and put the new ones in, she came to life! Then it was just a matter of tuning in the carbs from there.
Over the years, buying different boats and PWCs, I have found that in most cases, they all needed some type of carburetor adjustment. I can only figure that some - if not most - people attempt adjusting the low and high mixture needles and get them wrong almost every time. Once I look in the manual and get the correct settings, then it just takes a few minutes to dial them in and they run like they are brand new motors
If you know the plugs are not new, it's the simplest and one of the cheaper things you can check. Who knows - you might just fix the problem by doing that alone