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  1. #1
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    2000 520VX fuel line replacement?

    Dad recently bought a 520vx 225 Opti, going to replace fuel lines just for piece of mind due to poor running. Also going to pull the tanks, drain, and inspect pickup tubes. When we pull the seats what should we be looking for to pull the tanks as far as mounting hardware. Or would siphon the tanks and changing fuel/water sep be good enough? Wanting to do it right, she ll only hit 4200 WOT. Compression test checked out. Any tips, tricks, or hints would be appriciated! Boat rides like a caddy just running like a pinto!
    It's easier to ask for forgiveness than it is to ask for permission.

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  3. Member
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    #2
    Make sure he has the air injectors tested! If they're the older black ones, I would highly suggest having them replaced (the newer ones are blue). It's NOT cheap, but trust me, the black ones WILL fail over time. The next idea would be the reeds. The stock SS reeds on the Opti motors (NOT ProXS!) are notorious for cracking, chipping and breaking. Crankcase pressures run pretty high in these 3.0L motors, and thus the primary reason for failures in the reeds. I would also recommend having a good set of carbon fiber reeds installed. You can check the reeds by looking through the butterfly in the air plenum with an extended mirror and flashlight; it should be pretty easy to see any problems. Personally, I used Boyesen, and they worked out just fine. Those are the two biggest issues in the early Optimax motors, and as long as they are addressed and the motor is treated properly (regular service, quality fuel and oil, Quickkleen/Ring-Free in every tank, proper warm-up and cool down, especially in colder temps.), that motor should last a long, long time. Best of luck, and let us know what you find.

    RR_20

  4. Member
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    #3
    Could they be red injectors?
    It's easier to ask for forgiveness than it is to ask for permission.

  5. Member
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    Apr 2012
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    O'Fallon, MO
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    #4
    I always try to start with simple approach and then work into more complicated troubleshooting. If you recently purchased the boat, did you have Marine Mechanic inspect it? I would HIGHLY suggest getting this done...even if you already bought it. At least you'll know what to expect in terms of the motor and life span.

    Does the boat have a Hotfoot installed? If so....make sure it is properly set up so when the peddle is fully depresed, you at at full throttle where the cable connects to motor.
    If the boat has sat with fuel in it for long period, I would recommend draining all the fuel and replacing with fresh (non Ethanol if available). Add Sea Form or Mercury brand fuel cleaner treatment to first tank or two.

    Also check the prop and hub are in good order....
    Last edited by sugelle; 06-12-2012 at 12:18 PM.

  6. Member
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    #5
    No hotfoot installed at the current time. Going in the easiest first direction. Fuel lines, fuel water sep, clean and drain tanks, new primer bulb, check the fuel pump and valves for restrictions. Just make sure everything is good from the tank to motor.

    It ran good on tank one the first day, didnt act up till running tank 1 down to 3-4 gallons and switching to tank two. Tank two is when it started, tried switching back to tank one and no change in performance. Hit a few waves one time and she came to life for a minute then back to running poorly.
    It's easier to ask for forgiveness than it is to ask for permission.

  7. Member
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    #6
    Tanks are clean, pickup tubes are good, lines looked good but will be replaced, primer bulb also. Next step fuel/water sep filter, fuel pump
    It's easier to ask for forgiveness than it is to ask for permission.

  8. Member
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    Apr 2012
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    O'Fallon, MO
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    #7
    Again...I suggest if you can to take it to certified mechanic. If not, you could be just pissing money away and not solving your true issue. It wont hurt to replace the lines and filters, etc but it could be a fuel pump issue or something electronic that could be diagnosed using computer.

  9. Member
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    #8
    Also...try posting in the Mercury forum and look for a user named Don Weed...he has great insight and is a Mercury Master Tech with over 30 yrs experience. Be sure you give details of what year your motor is, etc.

  10. Member
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    #9
    Posted in the Mercury forum also, the basics we are covering as Don has suggested. We also have made arrangements to get the motor hooked up to the computer later next week.

    Here is what we took from the fuel water seperator.
    It's easier to ask for forgiveness than it is to ask for permission.