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Discussion Starter · #1 ·
Here's a big mystery that hopefully someone can solve for me:

I have a 2003 1100zxi that we just purchased. And it has a problem I can't seem to solve. Here's what I can tell you:

We took it out, for the first time, a couple of weeks ago, and it ran great for about an hour, then it just died. No running rough or anything, it was just like you pulled the lanyard. Then I restarted it, and it started right up and ran fine. I thought maybe I had just bumped the kill switch. Then, after about another 15 minutes, it died again. This time it was harder to start, but got it up again.

It started dying more frequently, and being harder to start. Eventually, my wife had to tow me in with her 1100 stx.

When we got to shore, I jumped off and looked inside for obvious clues. I didn't see anything that jumped out at me, so I closed it back up and (still standing next to it) tried to start the engine. It fired right up, and so I idled it in circles around me for some time to see if it would die. Ran fine, so I shut it off, climbed back on, and tried to start. It didn't want to start then! After a few attempts, it came back to life, and I ran it around for a bit before it died again. So I brought it to shore and just let it sit.

A few hours later, I got on and tried it again. It ran fine as I crawled out of the no wake zone, but when I throttled up it ran for about three seconds before it died.

At this point, I decided it must be fuel related. My reasons were as such:

1. No overtemp light, plus water flowing from weephole, plus no performance degradation (also, engine 'relatively cool' to touch.) make me think it's not a overheating issue. Also, problem didn't appear until after an hour of solid running at mostly full throttle, but happened again even after a 4+ hour period of rest/cooldown.

2. Engine cranks fine and fast, and sounds like it's trying to catch at the beginning of each starting attempt. I get a "burble". This led me to think the battery is fine, and that it's getting spark--at least initially for every cranking. The lanyard kill switch and ignition key have also been eliminated due to the fact that the starter wont turn over unless both switches are in working condition.

3. Engine runs smooth and good power output until it dies. I would imagine that if the issue were fouling plugs, it would run progressively (or even randomly) worse until it finally died, but this is not the case. Also, when the engine IS able to be restarted, it has full performance immediately, not like it was clearing fouled plugs or flooded. The boat has been converted to premix.

My presumption, in light of all of these things, was that I had water in the fuel tank, and that after an hour or so of bouncing around I managed to get a slug stirred up to where the fuel inlet could suck it in. I also thought maybe that water that had worked up in to the filter would account for why the jetski would run when I was standing next to it and holding it steady, but when I got on (bobbing up and down) it didn't want to start. And that also seemed like a good culprit for the boat running fine moving out of the no wake zone, but when I cranked it up and trimmed in on it's tail, it died a few seconds later.

So back at home, I siphoned out the tank (through the fuel line) and ran it through a water separator filter. And 10 gallons later, I saw not a drop of water standing in the bottom. Nevertheless, I dumped a bottle of Iso HEET in the empty tank (I don't know if the tank has a water/debris bilge below the outlet, but if so that would take care of what I couldn't pull out with the siphon.), then put half of the gas back in.

Then I hooked up a hose to the cooling inlet and ran the jetski on the trailer for 10-15 minutes without a hitch. We even rocked and rolled the trailer around to try to simulate some of the sloshing encountered on the lake. Decided that if I had any water in the gas before, I definitely shouldn't now, and the test run seemed to indicate this.

So today we took the jetskis out to the lake again. Mixed up a fresh batch of premix and refilled the tank. And the zxi started up right away, and ran just fine. For about 30 minutes.

Then it died.

Then I restarted it quickly, and it ran for another 10 minutes until a big wave jumped me hard enough that I pulled the lanyard. But then it didn't want to restart!!

So I waited awhile, cycled the ignition key (I don't know if there are any failsafes in the system that need to be reset--seemed worth a try) occasionally retrying the starter. Same results as before. Cranks fast, sounds like it's catching the first stroke (burble), crank crank crank. After about 10 minutes, I got it up again, and ran it for another ten minutes, when it died again, wouldn't restart, towed it in and put it on the trailer.

So does anyone have a suggestion for things to check that would account for this behavior? It's hard to conclusively check for spark while in the middle of the lake, but by the time I get it to shore or to home, it works fine and eliminates any possibility of finding ignition problems. But that's about all I can think of that's left. But I'm open to suggestions, even things I've previously discarded as possibilities.

One last thing: Both times the jetski ran fine until I pushed the auto KATS button. And it's not like it died right afterwards. But I would say within 5-10 minute of activating the auto trim, the boat dies. Probably just a loose coincidence, and I don't know how the two things could possibly influence each other, but stranger things have happened I suppose. Just a possible clue?

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Discussion Starter · #3 ·
I did figure it out, no thanks to the various pros. They all insisted it was internal mechanical problems, melted rings, fused pistons, etc. It took a lot of detective work, because the problem would ONLY arise when the boat was running in a lake (and dying in the middle of htme), which is not an ideal location for troubleshooting.

Anyway, the problem was this: A hairline crack had developed in the ignition switch housing, which slowly allowed water to seep in during actual lake running conditions. Eventually, enough water would collect in the switch housing to short across the terminals to kill the engine (essentially grounding the magneto). Then, after enough time had elapsed, the water would seep out the bottom of the switch and the kill circuit would be open again, allowing the boat to run (until collecting some more water).

Since the actual ignition switch for these boats is ridiculously expensive, I sealed the crack as best I could with epoxy and later silicone, and then I rigged a bypass switch inline with the "kill switch" line. Because you have to connect the "kill switch" contacts (you usually imagine disconnecting something to turn it off), my bypass switch allows me to break that connection again further down the line if water gets in again and connects the contacts.

If you want to verify, just take out your ignition switch. It's kind of a hassle, and there are two or three very small magnets, about the size of a grain of uncooked rice, that are spring loaded inside the switch itself. But it is SUPPOSED to be waterproof, even the wires pass through a rubber grommet on the bottom. If you see signs of corrosion or rust inside, you've located the problem. Or, just rig up a kill switch bypass (you can just snip the kill wire and reattach the two ends with a wire nut) and ride it until it quits, disconnect those wires and see if it runs again. That will tell you the answer as well, without the danger of destroying your ignition switch.
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