'02 GTX 4-tec misfires

[Sprailfire340]

New to pwc and 4 strokes in general. Recently purchased an 02 gtx 4-tec with less than 70 hrs on it. Acts like it is fouling plugs, but have replaced plugs several times with the same result. Must be something else.

Symptons - start cold (day or 2 of non-use) and it will idle and respond to throttle immediately, like it should. Upon engine warming (slighty) it will only respond under max throttle and at high rpm. Bringing it back to idle and then trying to go it only fires on 1 or 2 cylinders until max rpms and aprox 30+mph reached. Then non-firing cylinders will kick in and max acceleration is reached.

Any suggestions? Stator, coils, plugs???? Plugs are cheap, but would like to have some advice before I start replacing more costly parts.

Thanks for your time.

MJE

 

[devonte007]

I would start by replacing the plugs to determine if that solves your problem. I have read many treads from people with weird running engines, but after they replace the plugs everything is back to normal. I replace mine every season (about 25-50 hrs) to be on the safe side, its a cheap investment.

If new plugs don't work, then you'll need to dig deeper into ignition and/or fuel. Good luck and let us know what you find out.

 

[Sprailfire340]

On my 3rd set of plugs, also drained old fuel and running fresh 93 octane. No changes, still bogging when warm at low rpm. I'm at the dig deeper stage...thanks.

 

[Michael211_2000]

Get a can of Seafoam (at your local auto parts... OReilly's carries it I know), and treat the tank with it. Then try running it an hour or so at least and see if the problems clear up... it sounds like a fouled fuel system (yes I know you changed the fuel... in the tank! There's the lines and the injectors also though and gelled old fuel in the injectors can really mess you up).

ps. What were the old spark plugs like when you pulled and replaced them? Did they look ok, not fouled with oil or anything?

- Michael

 

[Sprailfire340]

Plugs looked good. I'm on third set and really can't tell which ones are fouling. Like I said all fire at high speed & rpm and they only misfire on take off up until 25-30 mph. They look clean and dry. I'll try the seafoam...been using it in my 2 stroke sleds for a few years. I've run at least 15-20 gallon fresh fuel through ski with no changes. Is it possible to manually clean the injectors if seafoam doesn't clear them up? Thanks