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  1. #51
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    When you say not turning over, do you mean no start? Or won't crank?

    You need to verify you are getting spark. Will need a spark tester to know for sure. You can get an in line tester for cheap.

    You can always pour a little premix (oil and fuel) down the carb throats to test if you ever suspect fuel supply issues.

    I don't know what the elec fuel pump may be doing to the elec system. So I cannot comment on that.

    The fuel pump can be tested with a vacuum pump. If you install the pump on the pulse fitting of the fuel pump and pump it up to around 3-4 inches of vacuum. it should hold indefinitely. If the vacuum falls, you have a leak in the fuel pump.

    As for your pulse fitting on the engine, make sure it's not loose. it's just a press fit. Make sure your pulse hose is as short as possible. Prob around 12" or less if possible. And make sure you're using reinforced fuel hose. Soft walled hose will collapse. The only other thing that would effect that would be low compression on the PTO cylinder. Low compression would give a weak signal for fuel pump diaphragm.

    You have a good Mikuni fuel pump with hoses routed properly, correct?

    I'm not a fan of in line fuel filters. The factory Polaris filter/seperator works great. if you don't have that, make sure the in line filter is oriented correctly. (fule flowing in direction of arrow on filter)

    You can pour a little premix fuel down the carb throats to prime the engine which will fill the fuel lines much faster than just cranking the engine.

    Fuel restrictor is in the return hose very close the where it connects to the carbs on 650's and 750's.(painted blue with return hose fitting located at back of carbs) The 780 carbs (painted black and return hose fitting located at front of carbs) have it built into the return fitting.

    Without the restrictor, you will have low fuel pressure at high RPM. That will lead to piston failure.

  2. #52
    So it will crank and wants to fire up and sometimes does and it is firing on all cylinders but Iím thinking more and more that it may be the elec fuel pump on there because when it wonít start and I pull the plugs theyíre soaked with pre mix. So maybe too much gas? I do have the triple mikuni pump and Iím thinking about switching it back over to see if that makes a difference. My pulse line does give pulse when you crank with my thumb on the pulse line you can feel the Pulses. I bought it with out the oem filter/ separator so I have a nice inline one that is oriented the correct way. As for the fuel restrictor there is a connection about 10 inches from the return out of the carbs, I just thought it was there to splice more hose but that may be my restrictor? Iím still a little confused about each return fitting out of the carbs like I said each carb have a very restricted hole where you hook up the return lines but youíre saying it needs one after the carbs? Iíll look online to see if I can find one. One more thing, I have stock settings on each carb and when It did start I pulled the plugs and the mag plug looked a lot more lean than the other two that were still kinda wet from fuel? So idk why that would be making it more lean than the others.. any input? Thank you again.

  3. #53
    I just went to get a plug tester that lights and at first only the mag was getting spark. Then the center was getting a low spark and no spark at the pto. Went through again and checked all my grounds and elec box, everything looked good. Tried it again same thing...

    Waited about 5 min and tried it again and got a really strong spark in the mag and center and still no spark at the pto. I was stumped so what the heck letís try the pto again. Boom! Lots of spark and the ski fired right up!
    Iím so confused on whatís making it do that. The first obvious questions is grounds? Well been over them multiple times! Fresh plugs and wires so no problem there.

    It seems to have a mind of its own but need to narrow this down before Iím out on the lake and it decides to take a crap on me.

    Any ideas?

  4. #54
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Looking through the manual, it does not mention the restrictor on 1992 or 1993 models. It does mention it in 1994. So you may not have one, maybe those small orifices you speak of build up the pressure. Not sure why they eliminated them in 1994 and went with the single one in the return hose?

    It's quite possible the elec fuel pump is putting out too much PSI. The engine was only designed to run 3-4 PSI at idle and maybe 6-8 at WOT. Most elec pumps I know of put out more PSI then that.

    There used to be a part in the fuel system called the autocock. (yes, for real, it was called that) It was recommended to be removed in a service bulletin in 1995. That may be the connection you see?

    MAG cyl usually does run hotter than the other 2 because of the magneto. Plus it also has a crank seal in there that is a potential source of an air leak.

    A leak down test can be performed if you suspect air leak.

    Make sure your engine mounting plate ground is good and clean. Also shake the engine and see if it might be loose. If the engine mount plate bolts loosen up, you will have a poor ground connection.

    The older models were known for the fuel tank sending unit to have issues. It used a large plastic nut to hold the sender in lace. It would crack and would have an air leak.

    Make sure it is good. Make sure the fuel hoses inside the fuel tank are in good condition. make sure the petcock is in good condition. make sure the fuel lines are in good condition. Make sure all fuel hose connections are in good condition.

    How about taking a few pics of the fuel sender, petcock, and your lines with filter.

  5. #55

  6. #56
    All the lines, both filters and pet cock are new. I bypassed the pet cock on the control panel and I will be getting a nicer one thatís not plastic haha.. I went through the elec box... yes once again! And to every end I found nothing wrong. I wanted to ask as well, could it be the ground from the elec box to the stator/magneto? And is just the ground wire replaceable? Thatís really the only ground I havenít tracked down because well when I had the engine pulled I never took the magneto off to look at the back and I know it would be such a pain at this point to do all that again just to track down one wire but I would be willing to at this point!!! As well I checked the fuel lines again and made sure everything was clear and itís getting fuel, when it runs it sounds amazing. But like I said ďwhenĒ it runs...

  7. #57
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    I know it's not normal to have the elec fuel pump installed, but it looks like it's installed well. I wonder if it's effecting the elec system. Might be time to try removing it from the elec system and run the Mikuni fuel pump. Not sure what kind of draw it's placing on the magneto.

    Sometimes people accidentally pinch the wires between the engine and mounts when installing the engine. Make sure you're not pinching your harness.

    You should be able to test your grounds with an ohmmeter.

    I hate to keep asking for pics, but it helps us to see what you're actually working with. Can I see the inside of your elec box please?

    You are using NGK BPR8ES spark plugs, correct?

    Have you tried cutting the spark plug leads back to expose fresh wire? Making sure you have a solid connection.

    Kill switch testing out good?

    Magneto testing out OK? Ohm testing the wires inside the elec box.

    Battery is in good shape?

    It sounds like you have the fuel system OK. So it appears you're chasing an elec gremlin now.

  8. #58

  9. #59
    No problem, I take a lot of pics especially when I removed the engine and I have the elec box cracked open right now so if needed I can take more.

    Yes I might go back to the triple outlet pump and see if that changes. Like you said who knows if itís affecting the magneto.

    I did ohm test the wires awhile ago and they all checked out. If needed as well I can go through them again.

    I do have the bpr8es spark plugs, brand new ones actually just because of this elec issue!

    The plug wires are good yes. And the kill switch is new with lanyard. It works as it should? But havenít multi meter tested it. I through it on and it worked. That would be a pretty simple problem to fix if it is.

    Brand new battery from about a week ago. Testing out as it should.


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