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Mercury 175 xri idles at 2500 RPM

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Old 01-01-2012, 10:23 PM
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Default Mercury 175 xri idles at 2500 RPM

Engine wasn't running when I bought it. Put a new fuel pump on it and it started right up. Now it idles at 2500 Rpm. The throttle body butterfly is shut and still idles high. What should I check next? Is there idle control Senor that could be bad? Any help?
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Old 01-02-2012, 06:44 AM
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i would look for a vacuum leak be careful you are probably running lean if it has a large vacuum leak
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Old 01-02-2012, 09:00 AM
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Thats what i havent checked. In fact I remember seeing a line that I had a plug on the end of it but looked like it fell off at some point.
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Old 01-02-2012, 10:01 AM
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Check the TPS Voltage, not sure what it should be on that motor, but if it is set wrong, it will idle high.
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Old 01-02-2012, 12:10 PM
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i think even if the tps sensor was dumping in to much fuel it would still need air to get to 2500 rpm not sure if it could idle that high on just extra fuel also have you checked to see what color the plugs are after it just idles for 5 minutes are they white or black?
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Old 01-02-2012, 12:12 PM
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also you might try a post on scream and fly i am sure you will find someone the answer i got a ton of help from those guys when i was running my 2.4 bridgeports
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Old 01-02-2012, 12:54 PM
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Quote:
Originally Posted by mach1magnum View Post
also you might try a post on scream and fly i am sure you will find someone the answer i got a ton of help from those guys when i was running my 2.4 bridgeports
I been on scream and fly. Just not a member. Guess I should join and post the question on there.
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Old 01-02-2012, 02:52 PM
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Quote:
Originally Posted by mach1magnum View Post
i think even if the tps sensor was dumping in to much fuel it would still need air to get to 2500 rpm not sure if it could idle that high on just extra fuel also have you checked to see what color the plugs are after it just idles for 5 minutes are they white or black?
Your probably right, I am not too familiar with the XRi motors.
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Old 01-05-2012, 12:08 AM
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Bought the Seloc repair book today! Hopefully this weekend I can get the boat out of storage and troubleshoot a few things.TPS sensor, air temp and water sensor. Hoping its not the ECU!
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Old 01-06-2012, 06:32 PM
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The throttle arm controls both the intake butterflies AND the timing plate under the flywheel. There are separate adjuster screws for both of them. Even a low butterfly openings, the timing advance alone will make those motors rev when there's no load on them.

Pull the cover. Disconnect the throttle cable from the big arm. Make sure it all moves as it is supposed to from idle position to wide open throttle position. Hold the arm and let somebody fire it up. See if you can move the arm far enough to let the motor idle down to under 800. Vacuum leaks can also contribute, but chances are that you have something out of adjustment from the throttle cable itself to something in the arm and actuators.

There are stop screws for max timing advance, minimum throttle plate opening, etc. Just take a look while you move the arm and watch it all. It will make sense.

You'll notice that the throttle plates only open a tiny amount as you increase the throttle until you get most of the timing in, then the throttle plates start opening.

MC
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