260 RXT Runs Rough Low RPM (5000) at FT Fouled Plugs

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Mike Sabaka

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I just pulled my 2012 RXT out for the summer. Got on the water and it ran rough, wouldnt go over 6k RPM. Added 8 gallons of fresh fuel with Heet additive. Changed plugs: plug 1 and 3 had wet oil on them and were fouled black; plug 2 was nice and dry and tan. What could cause this? Any help is greatly appreciated before I get robbed at dealership. FYI when I put it up last year for the winter it was running top notch. I did not fog the cylinders but did run out excess water before storing.
 
I’m pretty sure you fog the cylinders before storage to keep the cylinder walls pistons and rings free from corrosion. Maybe pull the plugs spray some xps into the cylinders and crank the engine in drown mode for ten seconds. Might free up a corroded ring.
 
Thanks for the reply. So you"re thinking a ring is not seating properly and allowing oil up into the combustion chamber? Two questions: what is xps? and what is "drown" mode? Thanks for any help, it is greatly appreciated.
 
Kinda taking a guess on the rings but yes, and XPS is the BRP anti corrosion spray recommended for fogging the cylinders when storing and drown mode is cranking the engine with the throttle held fully open disabling the electrical current to the coils. Ten second cycles is recommended.

I would think something like PB blaster or WD 40 would be something you could substitute for XPS.

4tecs don’t like fouled plugs, make sure you try again with clean plugs
 
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Kinda taking a guess on the rings but yes, and XPS is the BRP anti corrosion spray recommended for fogging the cylinders when storing and drown mode is cranking the engine with the throttle held fully open disabling the electrical current to the coils. Ten second cycles is recommended.

I would think something like PB blaster or WD 40 would be something you could substitute for XPS.

4tecs don’t like fouled plugs, make sure you try again with clean plugs

Thanks for the suggestion and information. In short, I fogged the cylinders, cranked in drown mode, put in new plugs, and put in injector cleaner. I let it sit a day, and it ran great the next morning. ----- I won't make the mistake of failing to winterize again. Thanks again.....
 
Yes, we had the 260 out all afternoon for several hours, running between 2/3 and WOT. I got lucky on this go around, new plugs didn't fix it outright but... Your advice was on the money. I think I had mild condensation in the cylinders over the winter which thankfully was corrected with the fogger, the regular fuel with ethanol deteriorated over winter and the Heet added alcohol back into the gas, and with 8 gallons of new gas and injector cleaner it started and finally after about 5 minutes at 2/3 throttle it started to run more an more smoothly as the new plugs, fuel, and fogger did their magic. It began to get it's "soul" back. Then it began running like the beast it is. I genuinely appreciate your post. I know this was simple in the end, but I had bad feelings early on since I had to have a complete BRP crate engine replacement 3 years ago under the extended warranty, under almost identical circumstances. Funny thing is the engine failed without a definitive diagnosis from the dealer or BRP. All maintenance was dealer performed prior to the failure.

To anyone who buys a new high performance BRP ski I recommend the extended 3 year warranty. It paid for itself with my engine replacement. And yes, we ride it like we stole it, after all that's what it was made to do!!
 
When saison is over, drain all fuel out and forget about the stabiliser. Recommended Mercury, Mercuiser procedure now. It is cheaper and better to start with clean fuel at the saison than "treated" fuel which still can give issues. Jetski not such a big deal, sport boat with 200 gallon tanks different story.
 
When saison is over, drain all fuel out and forget about the stabiliser. Recommended Mercury, Mercuiser procedure now. It is cheaper and better to start with clean fuel at the saison than "treated" fuel which still can give issues. Jetski not such a big deal, sport boat with 200 gallon tanks different story.
What is the "Mercruiser procedure?" Can you explain it? Thanks.
 
What is the "Mercruiser procedure?" Can you explain it? Thanks.
Today, with the ethanol based fuel, which creates a problem as it has the unique ability to bond with both fuel and water. The result is that where water would normally sit separate from the fuel in a contaminated system (where the water and fuel could be drawn off), water will instead mix with fuel containing ethanol which can lead to greatly reduced ability to support combustion (to the point the engine will not start nor run).

In the past Mercury/ Mercruiser recommended to keep fuel tanks full. However, that was when the moisture might be drawn off from a full tank IF it got that bad. We don't think people are willing today to risk 20, 50 or 100 gallons of fuel become contaminated with water and have changed our position. We think it is probably smarter to store the tank as EMPTY as possible, and then in spring prior to refilling the tank to use a primer bulb to draw off any water which has condensed over the storage period.

Personally, when servicing fuel systems on gasoline inboard or outboard engines it is amazing how much crap end up in the filters and fuel equipment and how quickly fuel lines deteriorate from this ethanol in the fuel. I recommend all my PWC friends and clients to store the PWC with empty tanks. The people not listening and following "fill tank completely before storage" are always the first to show up in spring time with issues.
 
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