GT40 electrical/fuel pump issue - HELP!

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  • TRIP
    Senior Member of PLANETNAUTIQUE
    • Nov 2007
    • 433

    • Costa Rica

    • 1997 Nautique Super Sport

    GT40 electrical/fuel pump issue - HELP!

    Hi guys,
    hope you can help me out here! Boat is '97 SS.
    Just recently had a fuel pump issue. Turned out to be the relay of the computer. Boat ran perfect, even better then before, which was already good. Happy me!
    Only a week or so, and a couple hours of use later: same issue it seemed (no priming of the fuel pump. Engine turns over but doesn't start). Not so happy me.
    Figured maybe the relay for the pump went out this time. Changed that out, but no.
    A friend told me to bypass the relay and connect fuel pump directly with battery to see if fuel pump worked. Tried that, but killed the whole engine. Somehow, I must have caused a short circuit. (Yes I'm an idiot, and I know it, that's why I usually don't try stuff like this myself). Engine didn't turn over anymore; nada.
    I checked the fuse between the battery and the engine, it's fine. Changed relays again; nothing. Really unhappy me.

    Had a mechanic look at it today. 3 Fuses (? 60, 15, 12.5) on front of engine were checked and are OK) He found out that the signal from the ignition doesn't reach the pump. He put a wire straight from battery to relay (computer's relay, if I'm correct) to the green/pink wire, so the pump engages as soon as you put ignition on. It now starts giving extra gas, but runs really rough. Doesn't idle.
    Mechanic says it's the spark plugs, but since it ran phenomenal only a week ago I don't think so. They might not be perfect (had fuel on them) but that's mainly of the rough running today, I think. Or they must have gone bad overnight.
    My guess is that wiring the pump straight to battery 'confuses' the computer, and that that's why it's not running well. Maybe not, or even probably not since I'm an idiot... but either way I don't think the main issue are the plugs.

    Any ideas and suggestions?! What might have gone bad when I tried hooking up the pump to the battery? What else to check or try?

    Thanks all!
  • TRIP
    Senior Member of PLANETNAUTIQUE
    • Nov 2007
    • 433

    • Costa Rica

    • 1997 Nautique Super Sport

    #2
    Changed spark plugs, just to be sure, but still the same.

    Then removed jump wire and it started again(!?!?). But ran same as the time it all went bad: surging at idle. As soon as you put it in gear it stalls. Managed to start a few times like this. Sometimes didn't start, then had to use wires to jump it again, with some extra throttle. Starts and runs super bad/rich, then as soon as I remove wires runs great, then stalls when I put it into gear. Pump still doesn't prime though, but starts anyway, sometimes.

    Buddy says IAC valve or MAP sensor maybe. How do I check those?
    Should I get this reader ?

    Comment

    • kylem03
      • Jan 2009
      • 178

      • Wisconsin

      • 1983 Ski Nautique 2001 1994 Sport Nautique 1995 Super Sport Nautique 2007 Nautique 236

      #3
      Hey Trip, I can’t help you other than to go look at the “poor mans GT40 diagnosis” on correctcraft fan. That should give you a good place to start looking at things. To me it sounds like it could be a fuel delivery issue with your pump but I’m no expert and electrical gremlins are tough. If you have the FUel control cell, I believe they have the high and low pressure pumps incorporated as one. My bet is that part of that system is malfunctioning causing a no prime/start/idle situation.

      Kyle

      Comment

      • TRIP
        Senior Member of PLANETNAUTIQUE
        • Nov 2007
        • 433

        • Costa Rica

        • 1997 Nautique Super Sport

        #4
        Thanks Kyle, I also feel it's something in that area. For the life of me can't seem to figure it out though! I've just gone through the poor man's GT40 thread couple weeks ago when it turned out a relay was bad. Gonna get back to studying it again!

        Comment

        • kylem03
          • Jan 2009
          • 178

          • Wisconsin

          • 1983 Ski Nautique 2001 1994 Sport Nautique 1995 Super Sport Nautique 2007 Nautique 236

          #5
          There is a linked post buried in the poor mans gt40 diagnosis linking to a thread troubleshooting the same issues as you. Turns out it was a bad ECM but I think the troubleshooting walk through will be telling to you. I’ll see if I can find the link and post directly.

          Kyle

          Comment

          • kylem03
            • Jan 2009
            • 178

            • Wisconsin

            • 1983 Ski Nautique 2001 1994 Sport Nautique 1995 Super Sport Nautique 2007 Nautique 236

            #6
            http://www.correctcraftfan.com/forum...40-fuel-supply. I think this might be helpful.

            Comment

            • TRIP
              Senior Member of PLANETNAUTIQUE
              • Nov 2007
              • 433

              • Costa Rica

              • 1997 Nautique Super Sport

              #7
              Found some good info in there, thanks! Will need an electromechanic to check things out for me, of course he doesn't read english... but this gave me a spark of hope again (all was gone, and I mean ALL. Ready to trade **** boat for a used System2). I'll keep you posted!

              Comment

              • TRIP
                Senior Member of PLANETNAUTIQUE
                • Nov 2007
                • 433

                • Costa Rica

                • 1997 Nautique Super Sport

                #8
                Click image for larger version

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                Turned out to be a bad contact. Cleaned those connectors with contact cleaner and pump started priming again. Sounded like music my to my ears!

                Comment

                • MTRBTR
                  Senior Member of PLANETNAUTIQUE
                  • May 2012
                  • 485

                  • MT


                  #9
                  I have a 97 sport. Its always something simple it seems but takes forever to track down. Glad you found it.
                  2006 SV 211 (Sold)
                  97 Sport Nautique (Sold)
                  89 PS 190 (Sold)
                  05 Fourwinns Horizon 180 (Sold)
                  89 Fourwinns 170 Freedom (Sold)
                  75 MFG (Sold)

                  Comment

                  • TRIP
                    Senior Member of PLANETNAUTIQUE
                    • Nov 2007
                    • 433

                    • Costa Rica

                    • 1997 Nautique Super Sport

                    #10

                    Oh the joy, the luxury, of turning a key and hearing the engine start... Amazing! Then first time coming on plane, pulling a wakeboarder... Life is good! Again...

                    Comment

                    • TRIP
                      Senior Member of PLANETNAUTIQUE
                      • Nov 2007
                      • 433

                      • Costa Rica

                      • 1997 Nautique Super Sport

                      #11
                      Well that joy didn't last long. One day, to be exact. Boat ran absolutely perfectly fine, started up each and every time without a glitch. Next time out the exact same issue occurred...
                      Found this today:
                      Click image for larger version

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                      Ground pin came loose (top left).

                      GT-40 ECM experts: what do I do?! I'm trying to find that thread about reviving ECM's, but any help is welcome!

                      Comment

                      • TRIP
                        Senior Member of PLANETNAUTIQUE
                        • Nov 2007
                        • 433

                        • Costa Rica

                        • 1997 Nautique Super Sport

                        #12
                        Well since the last post I had the ecm fixed, the pin soldered back. Worked great again! For about 1.5 hour....
                        Then had the ecm checked by a lab where they confirmed it went bad. Luckily in the mean time had ordered an ecm off Ebay and bought the chip that I had shipped to t.franscioni who put the software on it and sent it off to CR (mil gracias amigo!). Already have the ecm, hoping to receive the chip in the next 2 days.
                        Hopefully back in business soon!

                        Comment

                        • charlesml3
                          1,000 Post Club Member
                          • Jan 2008
                          • 2453

                          • Lake Gaston, NC

                          • 2022 G23

                          #13
                          Please keep us updated! This is a good mystery...

                          -Charles

                          Comment

                          • Infinity
                            Senior Member of PLANETNAUTIQUE
                            • Sep 2017
                            • 730

                            • Lake Norman - Denver, NC

                            • 2014 SV244 w/ ZR409

                            #14
                            Must be nice to be a boat owner in Costa Rica, one of my favorite places to relax. You get it year around

                            Comment

                            • TRIP
                              Senior Member of PLANETNAUTIQUE
                              • Nov 2007
                              • 433

                              • Costa Rica

                              • 1997 Nautique Super Sport

                              #15
                              It is! Indeed riding year round, and the wetsuit that I brought from the Netherlands has never been used. Hit me up when you're in the area!

                              Today I put the chip in the ecm and plugged it in, and... fired right up again! I'm being a bit careful now as I thought I had it all solved 3 times before. But I'm pretty confident that this time it's for real.
                              Could only let it idle for a few minutes today, but will take it for a spin and probably some riding tomorrow.
                              Hopefully to NOT be continued!

                              Comment

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