PWC Noobie - Water or Gas coming out of spark plug holes

ahackman

New Member
Hi All,
As the title mentions, I'm a PWC noobie - first time owning a PWC and now I have 2... One's a Polaris (sorry if that's a swear word around here) and the other is the one I have a question on. Should be noted that I have a decent understanding of engines, but first time dealing with PWC engines, so I'm clueless. Be gentle on me :)

It's a 1997 SeaDoo GTX 800. I traded a boat for these two PWCs and the guy said that this one has a spark issue, starting to understand what he meant. Let me take you back to last weekend.

I picked them up on Thursday, and started digging into the guy's theory that there was no spark on the seadoo. Took a plug out, grounded it, and turned over the engine - had spark. Put it back in, took the other out, grounded it, turned over the engine - had spark. Put both back in, turned on the gas, and boom - it fired right up. I was ecstatic! (only let it run for a few seconds, didn't have water flowing through it)

I let the battery charge up over night and had Friday off, so I took it out on the lake. Started right up, and I buzzed around for awhile, maybe 20 minutes, before the rain came in. It rained the rest of Friday, so I called it a day.

Now it's Saturday, beautiful weather, the wife and kids and I are ready to take both jet skis out on the water! I start with the sea doo, because hey, I had that one on the water yesterday, it should run... Nope - wouldn't start.

I spent some time on Sunday and Monday trying to get it to start, thinking it was a battery issue - hooked up jump pack, and still couldn't get it to start, so I gave it a break.

Today, I got a chance to dig into a bit more. I pulled the spark plugs out to test for spark again, couldn't really see a spark on the first one, and went to test the other one. I forgot to put the first one back in, and when I hit the starter, water, or possibly gas come flying out of the cylinders. Obviously, nothing should be flying out the cylinders, so I just let the starter pump whatever liquid was flying out, all the way out. Now it's pretty much fully out, just a slight mist (could be gas being pushed in? not sure). I put the plugs back in, which are probably now fouled out, and every now and then the engine will fire up for a second and die. After a few tries, I started getting a beep when hitting the start button, so I called it quits and came running to these forums for info.

My question is... If it's water, how would water get into the engine I did not flip the Jet Ski, and it ran GREAT when I had it out on the water (on Friday). Could it be a bunch of gas from trying to start it repeatedly on Sunday/Monday? My hands and smell like gas, but I assume there'd be some gas in the water too, if it was water.

I'm confident that if it was water, that it hasn't sat in there long enough to cause rust, only a couple days, and any help on what to do would be so greatly appreciated. And apologies for the long winded post here, wanted to paint you guys a picture as best as I could. I will definitely be putting some WD40 down the plug holes.

Thanks in Advance!
 
If its water I would be worried about possible having a cracked water jacket, but this is worst case scenario. The one beep when hitting the start button might mean the battery needs to be charged but im not very familiar with the gtxs
 
If its water I would be worried about possible having a cracked water jacket, but this is worst case scenario. The one beep when hitting the start button might mean the battery needs to be charged but im not very familiar with the gtxs
Would a cracked water jacket be caused from improper or lack of winterizing? I'm not sure if the PWCs were winterized by the previous owner.. something I should have asked...
 
Yup. If you dont pump antifreeze through the engine before the weather gets below freezing the water will freeze and expand in the engine and crack the water jackets.
 
Yup. If you dont pump antifreeze through the engine before the weather gets below freezing the water will freeze and expand in the engine and crack the water jacket
Would you say that it's possible that it could be gas, from attempting to start it repeatedly for a couple days with no success? I mean it was a lot of liquid.. I'd be surprised if it was all gas, honestly. I'm a bit sick today, so I can't smell great, but I'd bet if it was all gas, I'd be able to smell it...
 
FIrst, get a new quality battery and never use Jump packs on these as you can fry the MPEM.

You really need to determine if it is flooded with water or fuel so we can get you going in the correct direction.
 
Would you say that it's possible that it could be gas, from attempting to start it repeatedly for a couple days with no success? I mean it was a lot of liquid.. I'd be surprised if it was all gas, honestly. I'm a bit sick today, so I can't smell great, but I'd bet if it was all gas, I'd be able to smell it...
see how fast it evaporates
 
Alright, so chemistry tells me that water is more dense than gasoline, so it sinks to the bottom. I put two oil pans under the drain plugs (the drain plugs were already open, so some of had already poured out onto the grass.. oops.

Here's what I got after tipping the jet ski back and letting the rest drain out:
1717002714905.png
So the water was likely just water that was sitting in the hull from the rain over the last couple days - I've been dumping out the water pretty frequently. My new cover is being delivered today... :)

OKAY so it's gas. Admittedly, I tried starting it quite a bit. BUT IT'S NOT WATER?!
 
New batteries are being delivered on Saturday. Both PWCs had the flooded type of lead acid batteries.. which are now junk. Went with AGM.
 
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they weren't meant to be used with fuel that has ethanol in it so they rot from the inside out. when you pull them apart you'll see a ton of green goo inside of them. But all the green goo has made its way into the fuel filter inside the carbs and most likely gummed up the carbs as well. If you dont replace and rebuild the carbs the engine will run lean and take out the top end if not worse
 
they weren't meant to be used with fuel that has ethanol in it so they rot from the inside out. when you pull them apart you'll see a ton of green goo inside of them. But all the green goo has made its way into the fuel filter inside the carbs and most likely gummed up the carbs as well. If you dont replace and rebuild the carbs the engine will run lean and take out the top end if not worse
Understood - will get on that ASAP. Doesn't look like a super fun job, fuel line goes deep into the front of the hull. Plus it has a full tank of gas in it... :'(
Appreciate your help!
 
Just remembered there is a fuel shot off switch and it's a fuel pump system, not gravity fed. And the front tub can be removed.. so shouldn't be too bad of a job.
 
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and rebuild the carbs with genuine mikuni kits. best to order from osd marine to make sure its a genuine kit. if you use one of the knock off kits itll run like crap
 
2nd to all that Miki said. Worth repeating though is DO NOT JUMP START a Seadoo with MPEM. The MPEM (aka brain) is quite likely to get fried with no way to fix. Replace only with another old used one or the MSD 4255. I always disconnect the battery from ski/boat when charging battery. A 2amp trickle shouldn’t hurt it but who knows. 10amp charge or even worse a 50+ amp boost can cost you big time.

FYI.
The 787 have a single coil and both plugs fire at the same time. When running, one cylinder has a wasted spark at the bottom of stroke while the other fires near TDC.

Mikuni brand carb parts only!! Follow carb thread including build/buy a pop off test unit. If you check pop off before you start carb go thru I suspect you have very low values. Explains the full of fuel issue.
 
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