'97 GT-40 miss or sputter.

WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
edited February 12 in Boat Talk
Skid this evening. I skied first, boat ran great. I drove second set for a buddy and around the pregates the boat had like a pop sound, quick little surge after. Then again half way down the course and then tawards the end again. Made the PP surge a little. Skier got in and we just ran it down the lake no PP. It did a very intermittent miss (pop) after getting up on plane. Did not go 34mph..more like 25. Did it about 3 times length-ish of the course. Idles fine and having it in gear seems to be ok as well. Did put in 9 gallons before sets and a can of SeaFoam fuel additive (I do that a few times a year). Bad gas?? Check fuel cell (water/fuel separator)?? Drain cell?? Change it?? What else could it be?. Plugs and Wires and dis are not that old. Onset was certainly sudden.
>>> 11.25..a different kettle of fish. <<<
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Comments

  • DanEDanE Posts: 861 Crazy Baller
    edited February 12
    Start out by verifying you have the correct fuel pressure. Without that knowledge you could easily be caught running around in circles troubleshooting.
    WishAndre
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    Fuel pressure? If it's anything other then good, would that be a bit more then an intermittent misfire? Would think low pressure would not allow the boat to run wall at all. But I don't know. What's an indication of low pressure??
    >>> 11.25..a different kettle of fish. <<<
  • oldjeepoldjeep Posts: 3,345 Mega Baller
    Pull the distributor cap and check the contacts and rotor. Easiest check you can do.
    Chuck P
    Not a mechanic but I play one at home
    Wish
  • DanEDanE Posts: 861 Crazy Baller
    @Wish Depending on how far off it is it can give you everything from an occasional sputter to a no start situation.
    Point is, it is not monitored by the ECM and will not light up the fault lamp or generate fault codes. If you have access to a fuel pressure gauge you can rule out the entire fuel system minus the injectors with one quick measurement.
    Wish
  • Orlando76Orlando76 Posts: 936 ★★★Triple Panda Award Recipient ★★★
    I’d bet money on fuel cell. I’m not sure what fuel pressure should be but I’m guessing no less than 48psi throughout all rpm’s. ECM’s typically won’t tolerate much of a drop, maybe 6psi. If you don’t have a gauge the one from Harbor Freight will work and plug it into shraeder valve on fuel rails. A flat idle or even sometimes a long smooth acceleration won’t cause much of a drop in pressure. That motor should only require 2-3 plugs sets in its entire life. Today’s wires aren’t like the ones from the 60’s. Unless one was burned or gnawed on, the original set should last life of the engine. I’ve had dizzy’s in the past that didn’t like being in a boat, closed up in the motor box without being opened up and aired out every trip. But those seemed to be just points style.
    Wish
  • jhughesjhughes Posts: 857 Mega Baller
    Make sure it's really a misfire and not the S.L.O.W system kicking in intermittently from a bad oil pressure sender or temp sender. This system abruptly cuts power to protect the motor in a low oil pressure or high temp situation and it's quite unsettling when it kicks in. The check engine light would light at the same time if this was the case. If it's truly undoubtedly a misfire then ignore this.
    DanE
  • JetsetrJetsetr Posts: 229 Baller
    edited February 12
    Deleted
  • spicolispicoli Posts: 127 Baller
    A bad tac can make it miss ,i used to be able to tap on the face of tac make it skip fix new tac ,another time i had a worn spot in my main harness the big red power to dash it was under the floor and 8 hours trouble shooting to find it anyway both made it skip mostly from boat hitting bumps small ripples jiggling boat
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    What's the recommended interval for fuel cell filter to be changed?
    >>> 11.25..a different kettle of fish. <<<
  • DanEDanE Posts: 861 Crazy Baller
    @Wish Think the manual says yearly.
    Wish
  • gapullingapullin Posts: 23 Baller
    This is almost certainly a fuel or spark problem (I know that seems obvious, but bear with me). I don't recall Nautique fuel pressure off the top of my head, but it's less than the MC MPI systems. The guys at Discount inboard marine will surely offer this up for you. If pressure is good, it could easily be wet fuel. Sea foam will look after a little water, but more than a little will require methyl hydrate, and time to burn through the bad fuel. Decanting a few ounces of fuel off the fuel rail and allowing it to rest in a clear container will likely declare wet fuel (it sinks to the bottom, of course). Regardless, replace the filter in the fuel cell if it hasn't been recently done. The next thing to check is spark with a timing light, on each plug wire sequentially. I worked on a GT40 with a miss 2 years ago. Proved to be a bad distributor bearing, causing intermittent lack of contact between cap and rotor only at two cylinders. This condition was diagnosed with a timing light. And no, check engine will not be triggered with this issue. That said, the poster indicated the distributor is pretty fresh.

    I'd be guessing the issue is fuel, either bad filter or pump causing marginal pressure, or water in fuel. But the proper diagnosis starts with establishing fuel pressure and proper spark at all cylinders.

    How many engine hours, and is the check engine light on?
    Wish
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    No light and 1300hrs. As said, had just added 9 gallons to a frailly empty tank and added SeaFoam to that. It did run flawlessly the first set. Second set it started missing immediately on getting up to speed but only 3 times down the course and only a single split second miss. My gut says bad fuel or water in system. I've ordered the filter. Will drain cell tomorrow and check for water. Open to other thoughts and ideas.
    >>> 11.25..a different kettle of fish. <<<
  • Orlando76Orlando76 Posts: 936 ★★★Triple Panda Award Recipient ★★★
    http://www.correctcraftfan.com/Downloads/Pro_BOss_GT-40_Service_Manual.pdf

    Thanks to Keith Correctcraftfan.com might want to bookmark that page.
  • jakecuz23jakecuz23 Posts: 21 Baller
    This could be a dumb answer, but I would check you water intake to make sure it isn't plugged and overheating. Our boat gets clogged often and will sputter and loose power before the red overheating light comes on. Most likely you a fueling issue, but it only takes a second to check!
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    Ya, pretty religious about keeping an eye on that. Clear and flowing well.
    >>> 11.25..a different kettle of fish. <<<
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    @jakecuz23 I have that in a 3 ring binder. 👍
    >>> 11.25..a different kettle of fish. <<<
    jakecuz23
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    edited February 13
    No water on cell after draining. Was gonna take canister off but it won't turn. Yes I'm turning it the right way. Any ideas on how to loosen it without damage. How hardy are they??
    >>> 11.25..a different kettle of fish. <<<
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    Never mind...got it off.
    >>> 11.25..a different kettle of fish. <<<
  • jhughesjhughes Posts: 857 Mega Baller
    They are very thick. Get the big version of the Channellocks. Gets it every time guaranteed.
  • KillerKiller Posts: 358 ★★★★Quad Panda Award Recipient ★★★★
    If you haven't replaced before, There is the little fuel hose inside the cell. Pcm has a rebuild kit, might as well replace when you do the filter. They start to crack eventually
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    @killer, I looked all around it and it looks good. Am I missing something??


    >>> 11.25..a different kettle of fish. <<<
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    Used a pipe wrench and a few taps to the pipe wrench handle with a hammer. Filter looked pretty bad. New one on the way.
    >>> 11.25..a different kettle of fish. <<<
  • KillerKiller Posts: 358 ★★★★Quad Panda Award Recipient ★★★★
    @wish. Maybe it's good, won't really know until you take it off and play with it to see if it's failing. They will develop small cracks or holes eventually.

    If its original I'd suggest replacing.

    It's a $12 part.

    https://www.skidim.com/prodinfo.asp?number=RK045098
    Wish
  • WishWish Posts: 7,633 ★★★Triple Panda Award Recipient ★★★
    out of curiosity, about how many hours on a boat till a distributer cap and rotor go bad? Or is it just random-ish?
    >>> 11.25..a different kettle of fish. <<<
  • Orlando76Orlando76 Posts: 936 ★★★Triple Panda Award Recipient ★★★
    Random. But 100 hours might be a recommendation. Sounds like no luck with filter? Have you verified fuel pressure? If you suspect rotor and cap, give contacts a dusting with light sand paper until new one comes in.
  • oldjeepoldjeep Posts: 3,345 Mega Baller
    Random. Typically you can look at them and tell if they are likely to be bad. Burnt or corroded contacts underside of cap and rotor button.
    Chuck P
    Not a mechanic but I play one at home
  • MISkierMISkier Posts: 2,439 Mega Baller
    Sometimes a cap can get a small crack in it and will be affected by moisture. I had a truck that had difficulty starting/running after a rain. Changed cap and rotor and all was well. This was after I had the truck for 20+ years, probably about the same age as @Wish boat.
    The worst slalom equipment I own is between my ears.
  • fu_manfu_man Posts: 405 Crazy Baller
    The points on the distributor cap on my boat get oxidized regularly. I have to clean them yearly otherwise it will cause mis-fire, cough, sputter, lose power.
  • oldjeepoldjeep Posts: 3,345 Mega Baller
    @fu_man are you buying cheap auto caps, or are actually having that issue with brass contact caps?
    Chuck P
    Not a mechanic but I play one at home
  • fu_manfu_man Posts: 405 Crazy Baller
    On the brass caps.
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