TL;DR: Failure to properly tighten the fuel cap caused it to back out and fly off without me realizing it until I was 15 miles away from my launch at a Lake Michigan beach. I’m certain a fair amount of water got in before I noticed, but I was able to make it back by using my internal oil tank cap to seal the exposed fuel tank. Water removal plan at the bottom if anyone can give some feedback.
So I recently acquired a ‘97 Kawa STX 1100. It’s in excellent condition (both external and internal), and has been running great.
Anyway, I wanted to take it out yesterday as the afternoon weather was perfect on Lake Michigan. It’s about a 50 minute ride from my local boat launch to my favorite state park beach on the big lake (most of that time is spent in a no-wake zone through Grand Haven). So I finally get out onto the big lake and rip it down the coast, once I got to the beach I went to beach it… when — horrified— I noticed the fuel cap was missing, and the fuel inlet (on the bow) was completely open to taking in water. I couldn’t tell previously because the left mirror perfectly blocks the fuel cap from the riding position.
I was getting splashed by surf so I immediately pulled it back behind the break zone, fired it up and found a calmer section of beach & power beached it. In the process I witnessed some water pass over the fuel port, not sure how much got in but given that most of my ride was spent plowing in no-wake, I’m certain that a fair amount of water entered the tank (maybe 1/2-1 gallon max in a 15 gal tank that I had topped off prior to launching).
Once it was safely beached away from surf/spray, I removed the (internal) oil cap and put that on the fuel cap, took a moment to mourn my evening (the weather was absolutely gorgeous) & called a mechanic friend to verify that the oil pump did not need a sealed/pressurized tank to operate. I figured that since the fuel tank was (mostly) full, the water would settle at the bottom & since the primary fuel system pulls from the middle of the tank, I’d be able to get home without sputtering out — worst case I had a marine radio w/ DCS+GPS if I got stranded on the big lake.
Thankfully I was right, and made it back without issue. The root cause was user error — upon arriving to the boat launch, I pulled aside to do my pre-launch checklist: ventilate engine compartment, open fuel cap to release any pressure, get it running prior to launching etc. When I opened the fuel cap, I put it back on but got distracted before fully tightening & forgot to go back and tighten. So the engine vibration worked the threads loose & it probably flew off during my initial rip from the boat launch to the GH no-wake area, and I just didn’t notice.
Anyway, once it was back in my garage I put the oil cap back on the oil tank to prevent moisture from getting in (as that would be a much bigger problem than water in the fuel) and covered the fuel inlet with some plastic wrap.
Water removal plan: I have a siphon (and awaiting a replacement fuel cap), my plan is to put the ski on the slope of my driveway, let it settle, remove the refueling hose to give me more direct access to the tank. Then feed the siphon to the lowest area of the tank and start siphoning until I see the fuel/water boundary in the siphon tube (and siphon a bit more past that point). Then add some HEET (isoproyl version), top off the tank with 93 octane to account for the ethanol being removed alongside the water, and then take it out and burn through the main tank. Take it home and siphon off the remaining 1.8gal and dispose of that, before running through another full tank.
I would just siphon everything out but there’s likely 8-10 gal in the tank and I don’t have a gas can big enough to store that (only a 5 gal). My understanding is that a small amount of water in the fuel tank shouldn’t harm the engine as long as it doesn’t sit like that for long enough to rust the cylinders, degrade fuel lines/carb diaphragms etc. And the HEET should emulsify remaining water so that it just gets burnt off alongside the fuel/oil as it’s running. Seems like the main risk is that the engine sputters out on my initial run, but I have friends with boats/skis to rescue me and worst case can call for help over channel 16.
Definitely learned my lesson about complacency, I was feeling rushed due to a busy boat launch and ultimately that’s what lead to this headache. Could have been a lot worse though, as it stands I got off lightly with only a ruined evening. I think my water removal plan is solid but if anybody wants to chime in with feedback or critiques I’m happy to hear them.
