· Premium Member
Have you switched out the spark plugs and fuel filter? Do that first as that is the cheapest fix and is a very common cause to the problem you are having. If that does not work, check your impeller and shaft for damage. If those are fine, then check your engine compression. Also, drain the fuel and maybe see if water had not gotten into the fuel tank or fuel system somehow. What is your jet ski doing when it only goes 20 mph? Does it make any different sounds, bog out, what?