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Mixing spark plugs

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tomcat&family

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I am wondering if running plugs of different temperatures would have any negative affects. The front plug on one of my '99 GTX RFI's is fouling plugs, but the back one is fine. I was talking to someone about it, and they recommended installing a plug of a different temperature to replace the fouled one. He said that this was pretty typical with snowmobiles, and it should fix my problem.

Your thoughts?
 
It may be better to find the cause of the problem and fix it than to try and patch it up as it could result into other problems for you. :cheers:
 
Right, but I can't seem to find anything else wrong with it. Compresion is 150psi in both cylinders, I cleaned the RAVE valves, etc. This problem has been going on since 2003, as far as I can tell (I have the service records). The Sea-Doo dealer was not able to find a problem. It runs pretty well other than the fact that it is slightly slower than the other GTX (could be the fact that it had twice as much fuel) at a slightly lower RPM. Would the extra weight have an affect on the RPM's?

I run 93 octane fuel... would that have anything to do with this?
 
Has the fuel injector part [45] on the cylinder that is fouling? I am no pro but you seem to have a issue on that cylinder http://partsfinder.onlinemicrofiche.com/seadooforums/Seadoo_oem/Seadoo_PWC.asp?Type=13&A=67&B=15

How hard would that part be to check? That's one thing that I don't see mentioned in the service records. Here's what they checked several years ago:

"Checked unit over. Checked Rave valve. Compression, Spark, all were good. Put unit on buds found no faults, reset, close TPS and set to 6.7."
 
I am not sure if you can check it correctly as it could be leaking when there is fuel preasure or it could have other problems that may be able to be checked but I am not sure. good luck Robin :cheers:
 
If it is leaking, where would the leaking fuel go? Would I be able to see it on a hose? Or on something else? I smell no fuel in the hull of the boat.

EDIT: Well I found this thread:

http://www.seadooforum.com/showthread.php?t=135

Does anyone know of the 98 and the 99 GTX RFI's used the same engine? How do I go about cleaning an injector?
 
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If it is injecting more fuel, wouldn't my plug be wet? It's dry, and the others are slightly oily- "others" including the two plugs on the second GTX RFI.

I looked this up in my shop manual, and it doesn't seem too be a hard process on paper, though I still have no clue how to go about cleaning the injectors. I figure that I might as well clean them both if I can just so that I can rule them out if the problem persists. The problem is that it won't be as easy as it looks. I cannot even see the fuel rail because it is on the side and in a non-viewable area. I can see the fuel quick disconnect and the very start of the rail, but nothing else. This means that plugging the electrical connections back in will be a pain. Why can't these things be more accessible!

If this problem was major, wouldn't something be wrong by now? I mean, the ski still runs pretty well (only a few mph slower than the other). According to the service records I have, it has been going on since 2003, and 50-60 hours have been put on the ski since then. The compression is still perfect, too.

I decided not to do any work on it at this time because of the weather. There appears to be rain off to the east, and I really don't feel like having it start raining when I'm working on the ski. I almost want to build a cover for the boat lift, but even then... the wind we get here makes wrenching on the jet skis difficult. Oh well, there's not much I can do about it. I've got a great place to ride, so I shouldn't complain. I ended up taking the Arctic Cat Prowler out for a quick spin... I just had to drive something fun! :driving:
 
Sorry, I should have said other than the fouled plugs. I fouled my first plug after about 1.5 to 2 hours of use. I'm still on the second set, and they have upwards of 2 hours on them. The first plug fouled when I was idling. The guy I bought it from said that it had an issue with fouling plugs if it idled through the river out to the lake he ran them on. Me, I don't idle much. Being right on the lake, I can take right off (taking it easy until the temps get up, of course).
 
The threads are dark black and dry. I guess I'll have to take a peak at those injectors, as much as I don't want to.

How do I go about cleaning one without any of that fancy (and expensive!) fuel injector cleaning equipment? How much fuel is going to come out when I disconnect that connector for the fuel rail? I almost have a full tank of fuel in the ski at the moment.
 
Could be weak spark. coil, coil wire or spark plug boot. you could try and trim wires back 1/4 inch and see if it helps. :cheers:
Any visuals for this process? Being new to the world of Jet Ski's, I don't like starting something without knowing what I am getting into. I'm pretty mechanically inclined, but a few pointers and visuals never hurt. :)
 
If you have more than 2 spark plugs on this ski then I am lost. :confused:
LOL, I only have two on this ski. I have another identical GTX RFI that I am comparing this one to. 3 of the 4 plugs between the two boats are identical. The one on the front cylinder of this boat is the only one that is different.
 
Try and trim spark plug wire back reinstall and see if that helps. You could lay the spark plugs on the engine and spin engine over and see if you can see a weaker spark compared to the other but you may not be able to see a differance. :cheers:
 
If the inside of plugs [the part that is white when new] is very black when it fouls then you are not burning all of the fuel in that cylinder. the problem may be any were on the throtal scale and may not make the plugs to apear wet.:cheers:
 
When I ran my tests Monday on both skis to compare them (rpm's at idle, how they idled, top speed, rpms at top speed, etc.), the ceramic part of the plug on the front cylinder (the one in question here) was no darker than the rear one. If anything, it was lighter. The threads of the spark plug are what are dry and darker. The other plug has slightly oily threads. The test runs I made only consisted of about 5-6 miles with speeds varying from me idling in circles while watching the RPMs for several minutes to the max of 58mph that I was able to achieve with this ski. (For reference, the other GTX RFI with half the fuel hit 63mph with about 200 more RPM.)
 
Report back with the color of the plug after it has fouled.:cheers:
I still have the one I fouled on Sunday... I was kind of mad because they were new HGK higher performance plugs ($9 a piece!). I replaced both plugs with some standard HGK plugs and put the set I took out in the glove box of the boat... I'll have to run down there in a bit and grab them.
 
Here are some pictures of the plugs that got fouled up on Sunday. The one has obviously dried out by now.

1999gtxrfi1plugs002fu0.jpg


1999gtxrfi1plugs001jr3.jpg
 
Arg, three posts in a row! Sorry!

I just took the spark plug boot off from the front cylinder's wire. The end of it was a corroded (greenish), so I trimmed it back a little bit. I didn't take a quarter inch off because the corrosion only went a little ways. The wires are already pretty short, anyway (stock length, but short nonetheless). Should I do the other one as well? I didn't have to trim the wire's insulation back at all did I?
 
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