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  1. #1

    95 SLX 780 no start - water on plugs

    Been a lurker on here for quite some time and have searched a lot to try and figure out what the problem could be, or what i should do next.

    A little history first off:

    My 95 SLX 780 won't start. This is my first season with it. It has been running this year and has ran quite well, however the problems started last weekend after a long day of it sitting at dock in the rain.

    It fired up fine, idled fine to warm up a bit. I hit it to get going and just went blaaaa. Revved up to about 3500 then the more i pushed the throttle, the bigger the bog. Then it died. Wouldn't fire, had to tow it back. Pulled plugs, at the time i thought they looked okay. Still at the dock, no start. Drained the water separator just in case. Still no start... thought it was slow to fill the separator... but it filled eventually... no start. Towed it home.

    Pulled plugs, turned it over a bunch without the plugs in, left things open to dry out. Later in the week put the plugs in and she fires right up. Ok? hmmm

    Back to the lake this weekend, fired up and was boggy as above for a bit, but eventually after babying the throttle for a bit, got it up and running... full rpm, smokin across the water at 55MPH running great. Thought i had it licked! Then... the next day, fired up right away, idled a bit to warm up, hit it and it dies. Hit the starter, a little blip and then no start. No sign of life. Get towed back in to the dock.

    Initially we thought it was a fuel delivery problem. There is an in line fuel filter before the separator. I changed that. Verified that fuel was delivering to the pump ok. Pulled the fuel lines from the carbs. Its pumping fuel in fine out of all three. Just in case we pulled the pump, cleaned it out ( was pretty clean). We cranked it with the crankcase pressure line off the fuel pump and noticed some whiteish looking liquid come out. Couple spurts, and it was clear. It was very "water" ish looking stuff that came out of the crank case pulse line there. hmm. Put it all back together, attempted to start, no fire, nothing.

    Pulled plugs again. Cyl 1's plug looked good (close to the back of the ski)... not super wet with fuel though. Cyl 2 (mid) has visible signs of water droplets on the plugs...hmm! Cyl 3 (close to front of the boat) was the same as two. So we thought, hmm, water in the crank. Cleaned the plugs, verified spark was good on all 3. and now on to other things....

    Pulled the exhaust out, pulled the pipe, exhaust manifold and with the help of small hands got to the 3 crank case drain plugs. Cyl one (back of the ski) was clear overall.. Not much in there. hands smelled of fuel when we cranked with my finger by the drain. Pulled cyl 2 and a bit of stuff drained out. Felt very water like... did not smell like gas. Cranked the motor and more got pushed out. Same with cyl 3 (what a pain to remove that plug with the starter there!!!). Ok, so we figured we've got the water drained if there is any. lifted the ski on its side on the trailer and cranked it a bit to push out what was left. Put everything back together. Had a good feeling about this.

    Crank it, no start. Fuel is still flowing. Pull plugs again. Cyl 1 looks ok. Cyl 2 and 3's plugs have those water droplets again. Sigh.

    So now i'm curious... Where do i go from here???

    Could there be a bad gasket somewhere? head gasket on 2 or 3? perhaps gasket between the crank halves? Perhaps there's a crack in a water jacket in the crank???

    I'm really at a loss here and i'm not sure where to go next. I'm fairly handy, but i don't think pulling the heads and splitting the cases is something i want to tackle.

    Open to ideas! Let me know what you think!

  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada

    Good first post - lots of background info to work from.

    On the trailer, no garden hose, you should be able to get it started and dried out. Water in the crank case is bad for the bearings. Rust = engine rebuild.

    Do you have spark?


    Spark+compression+fuel should = running engine.

    When you got towed, how fast was the tow?

    Did you clamp off the water supply hose before the tow?

    Towing without pinching the cooling feed hose can flood the engine with water by back-filling the exhaust pipe.

    If you have spark and compression, prime the intakes with some fuel, see if it starts. You want to get some heat and RPM in the crank case, to get it dried out ASAP.

    Also put some fogging oil spray down the carbs to help protect the crank bearings. Fogging oil won't help you get it started, but it is better than nothing until you can get it dried out.

  3. #3
    Yeah... i know of the rust problem... so i can't let this sit forever!

    Spark - Yes, on all 3 plugs.

    Compression - Appears there is some form of it as a finger over each cylinder produces pressure.. i have no compression tester, but i can get one and test. I doubt its a compressions problem... but who knows.

    The tow was done with a rope hooked to my SL780 slightly faster than idling. it wasn't a long tow. When we removed the exhaust, there was a little bit of water in the waterbox, none in the pipe, no evidence of water in the manifold. The water supply hose was not clamped at either tow. The first time we towed it (last weekend) was done the same way and i was able to start after it drying out... or sitting for a day or two.

    I'll try priming it tomorrow if i have time. I have a fresh can of Polaris fogging oil so i'll get some down in there if it doesn't start up.

    Thanks for the response.

    Any ideas as to the cause of the water?

    Obviously i'm still open to suggestions/thoughts/opinions from anyone.


  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Normally i would suggest getting it running on land first, fog it, then start hunting for the water leak.

    Leaking gaskets at cylinder head or exhaust manifold would allow water into the engine.

    Since you already have exhaust manifold and pipe off, you may want to take the cylinder heads off and get a good look at the pistons and cylinder internals.

    Before you do, check and record compression. All plugs out, throttle held wide open.

  5. #5
    Are there any other gaskets that would allow water in to the engine like this?

    I'd pull the heads, but this is something i've never done before. Getting the pistons w/ rings back inside the head post inspection/replacement of the gaskets is what gets me.

    Also, there must be torque specs for the nuts at the base of the head, also exhaust manifold etc. Any idea where i can find these?

  6. #6
    Compression check says:

    125 - 125 - 130 psi.... looks good?

  7. #7
    Been busy but had time to check it this weekend.

    Turning off the fuel at the valve, i put premix directly down each carb and she fires up... runs for 2 seconds, then dies obviously due to the lack of fuel. Won't run on fuel from the tank. The fuel pump is delivering fuel.

    Going to check the gas filler cap/neck as apparently they can break or crack. I've siphoned the tank and i'll be putting in new premium fuel.

  8. #8
    Just to follow up on the solution here...

    It appears i had a cracked fuel cap or filler. I replaced it. There was TONS of water in the fuel. I replaced the fuel with new 91 octane "premium" and used a mityvac to suck fuel out of the tank to purge out the water in the system. Once it was sucking clear fuel i hooked things back up and it fired up. A few short test rides showed more water in the separator, but that has now gone away too.

    I ran a can of seafoam through it on 1/2 a tank this weekend to purge any leftover water and clean things out. Its been running fine since.

    Thanks for the help K447

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