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    2007 40hp Merc carb and compression questions

    Yamaha made a number of motors for the Mariner brand and the Mercury brand for many years. All the way up to the Mercury 225 HP four stroke model. Known by many as a Mercaha or Yamamerc. I can only report what Yamaha information says. Following is from the Yamaha service manual.
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    2007 40hp Merc carb and compression questions

    Looks to be a Yamaha power plant. Yamaha data for a 2007 model year F40 indicates the minimum compression pressure as being 87 psi. Yamaha data shows the idle mixture screw setting to be 2 and 1/2 turns out from being just slightly seated.
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    2007 40hp Merc carb and compression questions

    What is the engine serial number? How was the test performed? Motor should have been hot. Throttle wide open. Known good gauge. Battery full charged. Motor cranked until the pressure stopped rising.
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    Cost of carb rebuild

    Dying to hear how fuel that should be entirely/mostly in a gaseous state by the time it enters the combustion chamber can create a puddle.
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    Primer bulb issue

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    Primer bulb issue

    Yamaha's modus operandi seems to be if X parts are needed let's use X plus Y plus Z parts.
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    Primer bulb issue

    Three mechanical fuel pumps, one electric fuel pump and six enrichment valves.
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    Primer bulb issue

    Or perhaps a fuel injected model has been mounted on the frame of a motor that had carburetors.
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    Primer bulb issue

    Is the model of the motor not known? Is it a Yamaha or a Suzuki? MMM. Motor Models Matter.
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    Primer bulb issue

    If and when the motor seems to not be running right pump the primer ball to force gasoline to the motor. You doing with the ball what the fuel pump should be doing. Does the motor seem to run better when you do this?
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    Primer bulb issue

    All primer balls will get softer once the motor is running. The fuel pump(s) lower the fuel pressure within the fuel system from the pump inlet all the way back to the tank.
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    Yamaha 50 hp 2 stroke prop seal depth

    After all else fails...
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    Yamaha 50 hp 2 stroke prop seal depth

    Need a model identity.
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    Suzuki Kill Switch Issue

    In the back of your owner's manual is a wiring diagram. Kill switch is a simple open or closed device. Normally open for the motor to run. Closed to stop the motor. Or to prevent it from running. Ignition stop circuit is tied into the kill switch circuit. One wire from the two devices combined...
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    Suzuki Kill Switch Issue

    Is the model of the motor not known?
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    1994 l250 txrs 2 stroke

    www.yamahapubs.com or any Yamaha outboard motor dealer.
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    What’s this small tube do? Pics incl.

    The opening at the lower unit leading edge is the part that usually becomes clogged. As I recall a 1/8th" drill bit can be used to help auger any debris out. Turning the drill bit by hand of course.
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    What’s this small tube do? Pics incl.

    Just a matter of service. All airplanes of all kinds take off, fly and land based on pitot tube air speed. More important to them than GPS speed. Speed through the water is more important to some boaters than is GPS speed. Many boats don't have a GPS. Pitot speed is all they have. If that.
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    1990 250 2 stroke sea pro 2

    What brand of motor?
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    Yamaha controller

    There is a newer version of the 703 control box that includes a "press to shift" button. For those that feel the need for it.
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