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  1. #1
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    Default 1999 GTX RFI Keeps fouling spark plugs

    I am working on this Sea Doo for a friend of mine. He had the motor replaced a year ago and when he got it back it would foul both plugs within a few minutes. It didn't foul plugs before engine swap. The mechanic who switched engines said it was the oil injection system so he removed it and said to mix the gas manually. It is still doing it and now the mechanic is blowing him off. I noticed the crankshaft position sensor's bolt that holds it in place is missing, could this be the problem? If not what else should I check.

    Also, how do I run the sea doo out of water? Is there a place to connect a hose?

    Thanks

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    SeadooForum Pro El Toro 33809's Avatar
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    I'm sure one of the RFI experts will chime in here at some time, but I believe that I've read you CANNOT remove the injection on those engines. Well, perhaps you can remove it, but not if you want it to last or run properly.

    Here is a link about RFI's. Note entries 18 & 19 mentioning injection. In addition, the rotary valve shaft still need lubrication on models where the injection can be removed.

    http://www.seadooforum.com/showthrea...ght=RFI+premix

    I think you hook up the hose in the back by the jet pump. If not there, it would be inside the hull by the back of the engine. The procedure is, start the engine BEFORE turning the water on and shut the water off before stopping the engine.

    PS - welcome to the forum.

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    Last edited by El Toro 33809; 08-12-13 at 08:53 AM.

  4. #3
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    On some fuel injected systems... you can remove the oil injection... but on the seadoo's... YOU CAN NOT REMOVE IT !!! The reason is... the fuel injectors are on the back side of the bypass port... so almost no fuel will get into the lower half. They are known as stratocharged (stratified) engines. Sure, a small amount will get down just because of dynamics... but not enough to properly cool and lube the lower half.

    This is the same for a Di engine.

    So... if you didn't destroy the crank... hook it back up !!!!


    Now... if you have an RFI/EFI engine that has the fuel injectors on the intake (like the seadoo/Mercury EFI engine) then, you can remove the system, since the fuel enters the engine just like a carburetor, and flows though all the "Lower Half" parts. (known as Homogenized charge)



    Your fouling issue is probably from a leaking fuel injector. It's common for them to wear, and start to leak. Also... you need to pull the codes to see what is causing it to give you the warning light.

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    Tony
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    a common problem with those RFI engines is the injectors leaking when they're supposed to be closed, which washes the oil off the cylinder, fouls plugs, and burns up motors. if i were your buddy i'd be pulling the injectors off to be cleaned/tested, and reinstalling the oil injection system. if you premix the fuel in an injected engine the bottom end will not receive any lubrication and will burn up.

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  6. #5
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    Five-o-motor sports is where you'll did cheap injectors for you machine. Had the same problem, and lost a motor. As stated above, put the oil injection back on! Hopefully you didn't harm anything.

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    Thanks for all the help. I will hook the oil injection system back up. It probably hasn't ran more than 20 minutes with it unhooked. Hopefully crank is ok.

    Where can I get the fuel injectors cleaned and tested? Or is it better to buy new ones?

    Do you think the crank position senson not being bolted down could be a problem?

    Am I wasting my time working on this without a MPEM programmer?

    Thanks again

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  8. #7
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    If it were my ski, I'd spend the $140-150 and get new injectors. I wouldn't rely on 13+ year old injectors with a fresh motor.

    I'd say its a good possibility that the cps not being bolted down would give you troubles, considering how these motors vibrate.

    I'd repair these items and retest.

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  9. #8
    SeadooForum Hall of fame griz400's Avatar
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    60.00 ea. http://www.fiveomotorsport.com/0280150845-65lb call them with the part number that is directly on your injector

    also check your compression and make sure its right around 140 - 150 then id say its an injector problem, keep in mind that low compression will always fuel foul plugs, -- and you are very lucky that it still runs, you can never premix an rfi -- what i think is happening is, you are seizing motor with no oil, and its probably already hurt ... also if the injectors are going wide open at mid range, it only takes like 3 - 4 times it shuts off, then your cylinders will be trashed ...

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    Last edited by griz400; 08-12-13 at 05:32 PM.
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  10. #9
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    I will check compression before I buy injectors. I will post results.

    Is there a trick to getting to the injectors? They look tough to get to.

    Thanks

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  11. #10
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    I did a a compression test and both cylinders are 145 psi.

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  12. #11
    SeadooForum Hall of fame griz400's Avatar
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    make sure that you put back the oil injection, (it is critical) , here is a link to a thread i started here, -- it has alot of rfi info
    http://www.seadooforum.com/showthrea...jection-)-Spot

    the injector rail has 2 -- 10 mm bolts that hold it to the engine, 2 electrical connectors, and the 1 quick disconnect fuel line
    thats pretty much all that holds it all on .....

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  13. #12
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    Thanks for everyones help. I installed new fuel injectors and it starts and seems to run fine. I will get it out on the water soon. I hooked the oil injection system up and added the required oil. The seadoo has 50:1 fuel/oil mix. Is it ok if I go ahead and fill up the tank and leave the mixed gas in? Or would it be better to let the seadoo idle until it runs out of gas (out of water with hose hooked up)? One more question, there is a rattling up in the exhaust while idling out of water. It is not in the engine compartment. It sounds like it is up under the black plate that is on the bottom of seadoo. Is that normal?

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  14. #13
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    Get that fuel OUT! should never put premix in a fuel injected...anything.

    Just siphon it out as much as you can, then fill with fresh gas. A little residual will be OK. but nothing more than a couple litres.

    The rattling is actually from the jet pump. That is normal. Its the driveshaft sliding in and out when there isn't a load on the engine. When you put it in the water and have it above idle, it will go away.

    Also, never run a seadoo for more than a minute on the hose. The carbon seal will start to burn up. If you want to run the ski longer, run a second hose near the intake grate and spraying up towards where the shaft goes through the hull. That will keep the carbon seal cool.

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