Help with poor holeshot in my 2007 196 with ZR6

[ScottStewart]

Purchased this boat last season and loved that it was an absolute rocket out of the hole....great torque and up to 34.2 super fast which was great because our course has a short setup. Unfortunately in the last few weeks the boat suddenly became very sluggish, almost labouring when pulling out a skier. I have changed the fcc filter and wanted to change the primary filter but strangely my boat doesn't have one?!?, inspected and cleaned the screen inside the tank (it was pretty clean), adjusted the throttle cable, checked and cleaned the plugs (all looked to be in great shape), cleaned the spark arrestor, inspected all fuses (all good), changed out the battery and cleaned all connections (charging system steady at 14.2 to 14.4 volts), inspected TPS for cracks as i read a post saying this was a problem in 07 but it seems fine. Possible it's fuel as I filled up 5 cans at the same time, but my wakesetter has been having no problems on the same fuel. I also installed zero off which I was told would add hp from 375 to almost 400 but nothing changed and the issue was occurring prior to the zero off install. One thing I forgot to check is the rubber hose inside the fcc which can crack and happened on my 96. The boat starts, idles, throttles up fairly strong and tops out around 44kph. The only other "new" issue is when i put the boat in gear to tighten the ski rope the engine seems to oscillate. Looking for any ideas prior to taking the boat in to the dealer which might end up being an "end of season" decision. Thanks in advance for anyone that made it through the whole thread!!!!! (just wanted to provide as much info as possible)

Scott

[d_nodixon]

My 06 zr6 had a similar issue and it ended up being the plug wires

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[JayG80]

I have had 2 instances with the loss of horsepower in my 2002 Ski Nautique, GT-40. I'm not that smart but was able to finally diagnose both.

First case was a crack in the fuel line inside the FCC like your 96 had.

The most recent hp loss was due to a failed Centek Hull Hugger muffler. It was making a rattle and would pillow up when the engine started. The internal baffle collapsed and caused a back pressure. It had enough power to pull my wife in slalom course but was difficult to get me out of the water.

I'd start by checking the fuel pressures. Key On - Engine Off . At Idle, at 2,000 rpm and at high rpm. I also pulled the vacuum line off the fuel pressure regulator with engine running and watch for fuel pressure to climb.

The low pressure fuel pump does have an internal screen but doubt that is your issue.

When you were messing around the tank, did you check and clean the Anti Siphon Valve? Did you try going over 44 kph with Zero Off disabled?

I've never heard of ZO increasing horsepower

[ScottStewart]

Thanks guys!, just to respond, I did clean the anti siphon valve and it seemed to be fine, I also zero off was off when i ran it up to 44 MPH. i will check the hose in the fcc and fuel pressure and finally the screen in the low pressure pump. After that will look into the possibility of spark plug wires etc.........

[JayG80]

Original post says boat tops at 44 kph and your last post says 44 mph.

[ScottStewart]

Yes, my mistake, It was 70km, or 44mph....

[Neverenough]

I've heard of dirt dobbers plugging up fuel tank vent and doing the same thing. Might be worth a check.

[Quinner]

How is the cap and rotar?? Cap is pretty cheap, replace that if you are unsure when it was changed last. Is your prop and alignment OK?
That boat should run much faster then 44mph @ WOT

[d_nodixon]

No cap or rotor on the ZR6

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[Quinner]

LOL, thanks, my brain was still on Excal

[ScottStewart]

Well, since I know most (myself included) appreciate a follow up or fix to an engine issue I will happily say my bogging issue has been solved. Yesterday I read a separate post about a member describing his boat performance as running more like a 200hp boat than a 400 but generally still operating fine....this described my problem exactly. The fix for his issue was new spark plugs and although all my plugs seemed to be in good shape obviously they were done. I put new plugs in today and the boat is running like a champ again, power out of the hole and tops out at 48mph. Thanks to everyone for responding and trying to help out, I tried all of your suggestions! Cheers!