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  1. #1

    Default Mercury 115 EFI 4 stroke 2010 cuts out at 5,000 RPM

    Hi all I'm new to the forum and I'm hoping you might be able to help me out with this one to salvage my cabin rental fun next week.

    The motor runs well with good power up until it hits 5,000 RPM. Once it gets to 5,000 it alarms briefly, erratically drops RPMs to 0 then runs fine as long as I keep it under 5k.

    I can see a solid stream of water coolant shooting at the back at all times. It has the correct amount of oil in the oil is really clean. 100 hours on engine.

    I changed the spark plugs and replaced the inline gas filters. The old filters looked clean when I cracked them open. I did put some Quicksilver fuel injector cleaner in the tank and ran it for about 30 minutes less than 4800 but that has not seem to helped.

    Alarm from Mercury vessel view app:
    https://photos.app.goo.gl/pNdsdVb53nMdm8ZF8
    I did replace the camshaft sensor, since available on Amazon, but it made no difference.

    Cuts out at 5,000 RPM (drops to 0 RPM), video
    https://youtu.be/Z5bVdfYn1FY

    I have recently noticed that the lower unit is creating a whining noise. This seems to come and go. Video
    https://youtu.be/v7zIIcYRSKU

    Nameplate
    https://photos.app.goo.gl/RbX26zwAaCyXiM1o9

    Any help appreciated!
    Last edited by Mcclmark; 07-25-2020 at 11:18 AM.

  2. #2

    Default Re: Mercury 115 EFI 4 stroke 2010 cuts out at 5,000 RPM

    An update: RPM issue has gone away. AFTER new accidental rope-in-prop (new variable, new problem?), AFTER running idle on 5 gallons of fuel+quickleen on new tank and hose. I CAN get it up to 5500 RPM and once started runs great. So, it might have just been a gas problem.

    But.... New problem!: Upon startup it will turn over but NOT start on its own without using starter fluid spray on the air intake.

    It seems like the key push button choke enrichment is not working. I'm concerned that when the rope got caught in the prop it may have created a new problem but I don't know how to troubleshoot it.

    Any suggestions appreciated.


    Long History:

    - Added double dose of mercury quickleen to the gas and ran it for about 2 hours, no change. At low RPMs it always runs fine.
    - PM: New plugs, new battery, new fuel water separator, new water pump impeller kit (was >3yrs old). Oil change. Gear oil change. (all fluids were clear)
    - Inspected fuel line going from tank to motor, it looks clean inside
    - Attempted to remove gas cap while at high RPM's on like to see if it would allow me to go high RPMs (crude attempt to rule out anti-siphon valve on tank)
    - No change, still cut out.
    - New variable: When going in to dock got a dock rope stuck in the prop which killed the engine. Awesome! After cutting rope out it started up OK (was still warm) but still would still cut at ~5k rpm on way back
    - Picked up a new gas tank and added non-ethanol 90 octane with quickleen the next day
    - Wanted to ensure no water splashed into tank when removing gas gap on lake, and still wanted to rule out anti-siphon on built-in tank
    - Next day: Engine would turn over, but would NOT start or fire like it was NOT getting choked/enriched by the computer when pushing in key (115hp EFI)
    - Removed air filter (with sensor attached) and used starter fluid spray - IT FINALLY STARTED
    - Let it idle all morning at the cabin at the dock - ran great
    - after 5 gallons on external tank idling, filled it back up again and took it out and RPM issue went away, power returned (non-ethanol + quickleen)
    - Had to use starter fluid on air intake for it to start every time there after
    - if I turn it off for 10 seconds, it really struggles to start and needs to turn over for ~10 seconds before it fires
    - if I leave it turned off, it will not start without removing the air filter and using starter fluid

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