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    1997 SLT 780 carbs pumping fuel out oil fitting

    I just completed a full engine rebuild on a 97 SLT 780. The fuekl pump, carbs and the entire engine was rebuilt. The oil pump was replaced as well. I wanted to make sure the oil pump was working si i ran it for a bit with the oil lines disconnected from the carbs to see if oil was pumping. (the fuel is pre-mixed for break-in). Now when i run the motor, fuel is pumpng out the oil line connection on the carbs. What would cause that?


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    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Fuel is coming out of the oil line instead of oil being pumped in? Is that correct?

    I would assume there is no oil pressure then.

    I believe the later 780's didn't have a check valve on the oil lines and could actually cause this to happen.

    Make sure you oil tank is full, vent line is clear, and that you "bled" the oil pump to purge any trapped air.

  3. #3
    You are correct, fuel is pumping out of the oil inlet fitting on the carbs. No oil lines are connected to the carbs at this time.
    I only ran the ski 3-4 seconds because it's not in water, maybe this was not enough time to pump oil up the lines?
    You are correct, no check valve on the 1997.
    The oil tank has 1 gallon of new oil in it after being completely drained. The pump has been bleed.

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    Take a squeeze bottle and fill the lines with oil. If you pull the line off the pump, squirt oil down the line until it comes out the end and then reinstall it on the pump the line will be full of oil.

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    I'm addicted to Polaris PWC ghostinstallations's Avatar
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    Quote Originally Posted by mudweiser99 View Post
    I just completed a full engine rebuild on a 97 SLT 780. The fuekl pump, carbs and the entire engine was rebuilt. The oil pump was replaced as well. I wanted to make sure the oil pump was working si i ran it for a bit with the oil lines disconnected from the carbs to see if oil was pumping. (the fuel is pre-mixed for break-in). Now when i run the motor, fuel is pumpng out the oil line connection on the carbs. What would cause that?
    I was under the impression that there were check ball valves in the carbs to prevent this. Maybe I'm wrong.

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    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by ghostinstallations View Post
    I was under the impression that there were check ball valves in the carbs to prevent this. Maybe I'm wrong.
    I don't believe ther ere check valves on the carb fitted oil fitting. The oil fittings on the intake maniofolds, yes. (older models)

    I was told that these can be an issue if you don't use your fuel shut off valve. If the fuel tank vents are clogged and the fuel tank builds enough pressure, fuel will actually push up into the oil tank. Just as he described here.

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    I'm addicted to Polaris PWC ghostinstallations's Avatar
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    Quote Originally Posted by xlint89 View Post
    I don't believe ther ere check valves on the carb fitted oil fitting. The oil fittings on the intake maniofolds, yes. (older models)

    I was told that these can be an issue if you don't use your fuel shut off valve. If the fuel tank vents are clogged and the fuel tank builds enough pressure, fuel will actually push up into the oil tank. Just as he described here.
    From his description, I don't believe he has fuel going into the oil res, but does have fuel coming out the fitting with no oil lines connected but the engine running. But based on what you are saying, it sounds like there are not check valves. If this is the case, then it would be normal for fuel to come out the oil inlets in this case.

  8. #8
    There was fuel in the oil revivor. It was drained and re-filled. I just bought the craft, so i do not know the history of it. When i bought it, i did have to rebuild the carbs, fuel pump and replace the oil pump. The pump worm gears were ground off. This was the first time i have fired the motor since i rebuilt it.

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    Quote Originally Posted by mudweiser99 View Post
    There was fuel in the oil revivor. It was drained and re-filled. I just bought the craft, so i do not know the history of it. When i bought it, i did have to rebuild the carbs, fuel pump and replace the oil pump. The pump worm gears were ground off. This was the first time i have fired the motor since i rebuilt it.
    Careful with running the motor even for a few seconds without the oiling system installed and functioning. You should probably be running a tank of premix until you are confident the oil system is functional and reliable..... But you already said that you were didn't you.....
    Last edited by BlueFishCrisis; 08-28-2012 at 02:50 PM. Reason: Cause I'm stupid

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    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by mudweiser99 View Post
    There was fuel in the oil revivor. It was drained and re-filled. I just bought the craft, so i do not know the history of it. When i bought it, i did have to rebuild the carbs, fuel pump and replace the oil pump. The pump worm gears were ground off. This was the first time i have fired the motor since i rebuilt it.
    How do you know the mating gear on the crankshaft was not also damaged?

    How could the oil pump gear get damaged?

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