2005 496 HO wont go above4000 RPMs
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2005 496 HO wont go above4000 RPMs

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    Senior Member JETDOC's Avatar
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    Default 2005 496 HO wont go above4000 RPMs

    My port engine is strong until about 3800 rpm, starboard is fine. Happened last 2 times out, had the Sunny 3 years now & never an issue with this engine. I put the rinda scanner on it & no abnormal fault codes, said 100% power avail from ecm. Did the induced misfire test on all 8 cylinders 3 times, all passed. IAC valve test good. No smoke or abnormal sounds. Leading me to believe its not getting enough fuel, changed the 3 screw drop in fuel filter, same results. Thinking now its the fuel pump. Any suggestions? The fuel pump looks like a real pain in the butt, any suggestions? or is it easier to remove the whole housing? Am planning on swapping to the other engine & water testing instead of throwing cash at parts I may not need. Thanks for any help.
    2005 Sunsation 32' MCOB, 496 HO'S

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    Senior Member Hullshot's Avatar
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    Quote Originally Posted by JETDOC View Post
    My port engine is strong until about 3800 rpm, starboard is fine. Happened last 2 times out, had the Sunny 3 years now & never an issue with this engine. I put the rinda scanner on it & no abnormal fault codes, said 100% power avail from ecm. Did the induced misfire test on all 8 cylinders 3 times, all passed. IAC valve test good. No smoke or abnormal sounds. Leading me to believe its not getting enough fuel, changed the 3 screw drop in fuel filter, same results. Thinking now its the fuel pump. Any suggestions? The fuel pump looks like a real pain in the butt, any suggestions? or is it easier to remove the whole housing? Am planning on swapping to the other engine & water testing instead of throwing cash at parts I may not need. Thanks for any help.
    Take the scanner out with you and monitor motor, chances are it is seeing a value it doesnt like and reducing power. Oil, water pressure, coolant temp, or exhaust temp? Watch tips and make sure it's seeing 100% of range also

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    Senior Member JETDOC's Avatar
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    What page on scanner is used for current faults at power? Is there a fuel pressure setting? Or a way to mount a press gauge? Thanks
    2005 Sunsation 32' MCOB, 496 HO'S

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    Junior Member dos daytona's Avatar
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    Default Cool fuel 2 or cool fuel three?

    The schrader valve is under the plastic cover, starboard side fuel rail with a plastic cap on it. Fuel psi should be no more than 44 psi and no less than 40 psi when testing with the fuel reg hose blocked off. If you don't have any alarms or when you key the engine on ,are only one beep..... there are no hard faults affecting performance at this time. Three beeps something is stored= problem. Fuel psi is not going to show up on any scan tool and must be tested.

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    New here Beer:30's Avatar
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    Quote Originally Posted by dos daytona View Post
    The schrader valve is under the plastic cover, starboard side fuel rail with a plastic cap on it. Fuel psi should be no more than 44 psi and no less than 40 psi when testing with the fuel reg hose blocked off. If you don't have any alarms or when you key the engine on ,are only one beep..... there are no hard faults affecting performance at this time. Three beeps something is stored= problem. Fuel psi is not going to show up on any scan tool and must be tested.
    Awesome. You beat me to it.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    Senior Member Hullshot's Avatar
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    Fuel pressure stopping motor at exactly 4000k every time it happens? Possible but not likely. Computer is likely the only thing that will stop motor at a given rpm? 80% power?

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    New here Beer:30's Avatar
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    Quote Originally Posted by Hullshot View Post
    Fuel pressure stopping motor at exactly 4000k every time it happens? Possible but not likely. Computer is likely the only thing that will stop motor at a given rpm? 80% power?
    Do we know there is just not quite enough pressure to maintain the engine above that level? Most issues with an EFI motor end up being fuel-supply related. If you baseline the KOEO fuel pressure - ITS AN EASY THING TO RULE OUT.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    gn7
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    Quote Originally Posted by Beer:30 View Post
    Do we know there is just not quite enough pressure to maintain the engine above that level? Most issues with an EFI motor end up being fuel-supply related. If you baseline the KOEO fuel pressure - ITS AN EASY THING TO RULE OUT.
    Put a carb on it

    Sorry Beer, I couldn't help myself



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    Senior Member JETDOC's Avatar
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    thanks guys for the info, will have to config a fuel press guage setup this weekend. the way I understand it is there no way to press test the low press pump, so I guess if the rail has good press the low pump may not be supplying enough. If water testing what kind of press will there be At operating about 3000 rpm? Anyone ever swap out the whole assy, may do that for t/s'ing?
    2005 Sunsation 32' MCOB, 496 HO'S

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    New here Beer:30's Avatar
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    Quote Originally Posted by JETDOC View Post
    thanks guys for the info, will have to config a fuel press guage setup this weekend. the way I understand it is there no way to press test the low press pump, so I guess if the rail has good press the low pump may not be supplying enough. If water testing what kind of press will there be At operating about 3000 rpm? Anyone ever swap out the whole assy, may do that for t/s'ing?
    I bought the OTC Master Fuel Pressure Test Kit. It had every fitting known. Real easy with quick-connectors. I have several vehicles, so I know I would need it from time to time. If YOU are gonna be wrenching on anything EFI, you will want a kit like this or SOME WAY of troubleshooting fuel pressure.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    Junior Member dos daytona's Avatar
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    Default pcm in power reduction mode

    Quote Originally Posted by Hullshot View Post
    Fuel pressure stopping motor at exactly 4000k every time it happens? Possible but not likely. Computer is likely the only thing that will stop motor at a given rpm? 80% power?
    Fyi...if the warning system is working the pcm will always sound a alarm went putting the engine into guardian mode if a electric sensor problem/voltage ref is out of range..... 555 pcm or later....

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    Junior Member dos daytona's Avatar
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    Default low psi pump

    Quote Originally Posted by JETDOC View Post
    thanks guys for the info, will have to config a fuel press guage setup this weekend. the way I understand it is there no way to press test the low press pump, so I guess if the rail has good press the low pump may not be supplying enough. If water testing what kind of press will there be At operating about 3000 rpm? Anyone ever swap out the whole assy, may do that for t/s'ing?
    The way to test the low side is with a vac gauge between the anti siphon valve and fuel inlet. KOEO a few times and read the gauge...if you see more than 3 inch or more you have a problem with the boat not the engine at this point. If its less then less than 3 inches then do the same thing again with the fuel hose pinched in front of the anti siphon valve on the tank (stop all fuel flow read the gauge) . I think the vacuum should read around 10 or more on the gauge...the low psi pump is ok...good luck & hope this helps .....

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    Senior Member JETDOC's Avatar
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    Thanks guys, is the 555 pcm, no beeps or faul codes. rinda shows 100% pwr avail. my weekend projecdt now
    2005 Sunsation 32' MCOB, 496 HO'S

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