2002 GTX Backfire and barely runs

[Jeff_5_7]

I have a 02 GTX and it set for about a month of so and now it wont hardly run.

Compression is 180psi on all 3 cylinders
All fuses in MPEM are good
No Trouble codes (it was showing a p0231 but it when away after i pulled the mpem out and checked all the fuses.

It hesitates to start and when it does it wont rev past like 3k rpm and honestly it just runs like crap. This is all on the trailer in my shop. It will backfire and pop really loud as well as have alot of white smoke around it seems.

Here is a picture of the spark plugs
From left to right Cylinder 3 2 1

This is after about 5 mins of running on the trailer with multiple starts. If i start it and dont hit the gas it will just die.


I stuck the plugs into the coils and grounded each one indivually and got a spark off of all three so is this a fuel problem?

 

[Michael211_2000]

Jeff, buy new plugs and put them in and try it. These 4TEC engines ruin spark plugs in short order, most people report having to change their spark plugs every year. And just because they will spark doesn't mean they'll spark under compression, I know this for a fact it bit me in the butt about this time last summer... I checked every plug 1 at a time with them all out of the engine, put them in the coil and grounded them around the threads and cranked the engine they each one sparked looked perfect but engine still ran like crap with them installed.... put brand new set of plugs in, runs like a champ! No idea why.

So just do it, change the spark plugs throw those in your hand away. Then report back if it makes a difference or not.

Also do you treat your fuel with SeaFoam or Stabil or something? You really should, every fillup no matter what time of year or when you plan to run it next... an ounce of prevention is worth a pound of cure!

- Michael

 

[Jeff_5_7]

Where is the best place to get plugs? I cleaned them really well putting them in the sandblaster. Trick My dad showed me from the iarplane world. Anyway i was readinhg some others post and i think for a few bucks its worth a shot.

 

[Michael211_2000]

You can order them online from seadoo warehouse or sbt or ebay even, if you don't have a local SeaDoo dealership to get them in person. You might can take one to your local auto parts and while they may not have it I bet they can get it in a day or two.

My old plugs looked like brand new, the electrodes weren't dirty nor worn at all... yet the engine would barely idle and would surge and miss above idle. Even more interesting is that my spark plugs failed during my only high-speed near WOT run August 2011 about this time, the lake was flat as glass and I decided to see how fast this RXT could really go... at ~67mph near WOT it seemed like the engine suddenly died, rpm's dropped wayyy down suddenly and as the RXT slowed down to ~30mph I realized the engine hadn't died was in fact still running if only barely... it surged and sputtered all the way back to the boat ramp (luckily I wasn't far away from the boat ramp when this happened). I could not find anything mechanically wrong with the engine, it would start and idle really roughly the plugs looked clean and weren't worn in fact I thought they WERE my new spark plugs I thought I had put them in previously... when I went to pull the "old" plugs from the spark plug storage thingy in the rear tray though, I found my NEW plugs were still in there (the screw-on electrode caps were still on them... duhhh!). I put the new plugs in, it runs like a champ again hasn't given me any problems at all this summer since putting the real new plugs in. Why did my previous set of spark plugs, which looked just like the new ones and did all 3 spark when I tested them, suddenly start making the engine run all wrong that last outting of 2011? IDK! Nobody knows in fact. It's just a fact that the spark plugs will go bad in these engines and won't spark consistantly under cylinder compression.

- Michael

 

[Duane72]

Where is the best place to get plugs? I cleaned them really well putting them in the sandblaster. Trick My dad showed me from the iarplane world. Anyway i was readinhg some others post and i think for a few bucks its worth a shot.

Jeff... DITTO what Michael said! SeaDoo recommends plug replacement every year as part of annual maintenance with oil change. The plugs can look perfect in every aspect and suck in performance. Who knows why. I have bought the NGK DCPR8E plugs at both Auto Zone and Advanced Auto at decent prices. Just check them BEFORE you leave the store. The same plug comes with both a solid terminal nut or removable terminal nut (on the end the coil plugs onto). You need the removable. They are both DCPR8E, but one is labeled "4339" and one "4179". The 4339 is removable, the 4179 is solid.

The ethanol in today's fuel will fowl plugs almost guaranteed in these smaller machines. Anything from lawn mowers to motorcycles are having problems with plugs fowling much more regular. Change the plugs every time you change your oil and use a stabilizer in your fuel with every fill up and you'll save yourself a lot of headaches.

 

[door54]

Agreed.
You have one, two, or three problems. Spark plug is the answer for each. Replace them all, toss the old ones.
My experience was similar. Unit ran great last outing...put it in the water...it starts backfiring and running like crap. Reminded me very much of a plug fouled, bogged down 2 stroke that just needed a WOT 'blow out' run.
So thats what I did. And after the run, it ran great the rest of the day...until the next morning. Same problem. So I repeated the WOT process with the same results. Ran great. But it had me scratchin' my head all day.
Next morning same problem, but this time I couldn't 'fix' it. Changed the plugs. Bingo.
Dying plugs display various symptoms, so we share our stories so others benefit.

Duane and Michael offer up some spot on advise re: plugs, but they both advocate additives in each and every tank, which is counter to the responses delivered in a thread titled "Fuel Fundmentals...the stuff we put in our rides" that I submitted a week or so ago. Others say 50 hours or more on additives. I think the jury is still out on this matter.

 

[Duane72]

Agreed.
Duane and Michael offer up some spot on advise re: plugs, but they both advocate additives in each and every tank, which is counter to the responses delivered in a thread titled "Fuel Fundmentals...the stuff we put in our rides" that I submitted a week or so ago. Others say 50 hours or more on additives. I think the jury is still out on this matter.

I won't argue and say you're wrong that's for sure. I can't give scientific proof behind my additive in every tank position. All I can give is experience. I run it constant in anything smaller than my car for the most part and it keeps the issues down. My motorcycle though, I do run several tanks between if I am riding it a lot. I will say that if the gas is going to sit for any more than a couple days additives will help. The newer ethanol-infused fuels break down quick.

 

[Michael211_2000]

but they both advocate additives in each and every tank, which is counter to the responses delivered in a thread titled "Fuel Fundmentals...the stuff we put in our rides"

It will not hurt anything to use 1 stablizing additive of your favorite flavor per directions in every tank of fuel year round... another case of "an ounce of prevention is worth a pound of cure". Compared to the cost of a gallon of gas, the additive is cheap.... compared to the labor and parts costs of a fouled fuel system, the additive is REALLY cheap!

Remember: If bad weather hits or work gets in the way it may be weeks between starting these watercraft up and riding them, better to have already treated fuel in the tank and injection system than not IMHO.

Regards.

- Michael

 

[door54]

Appreciate the 'comebacks' guys...It just makes sense to me to follow an additive regiman....but with the responses I got earlier I assumed that I was just overthinking things. I'll use a 5.25 oz LUCAS Treatment/cleaner serving size per tank. It's not uncommon for my rides to go 2-4 weeks without seeing water.

Thanks once again

 

[Jeff_5_7]

Spark Plugs fixed it you guy are awesome but apparently when it back fired it shatter the plastic elbow at the end of the exhuast so looking for parts once again.

 

[Michael211_2000]

Glad to hear new spark plugs cured the problem... '02 GTX's used a plastic elbow at the end of the exhaust manifold? My '06 RXT has a stainless steel J-pipe at the end of it's exhaust manifold, which seems like a much better thing IMO.

Try Ebay, you may get lucky and find a good used one listed.

- Michael

 

[Michael211_2000]

Does the '02 GTX have a 4TEC engine, or is it a 2-stroker? I'd presumed this was a 4-stroke model you've been dealing with this being the 4-Stroke PWC forum.... now I'm confused.

- Michael