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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15905
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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2006 mercury 115 rough idle, Just bought boat. Boat has been

Customer Question

2006 mercury 115 rough idle
JA: Thanks. Can you give me any more details about your issue?
Customer: Just bought boat. Boat has been setting up drained all the gas out put new gas in. The boat is running rough at idle and at 2000 rpm on the water muffs. Checked plugs they were black as tar. And their autolite plugs plan to get new plugs tomorrow but could this be my problem motor only has about 50 hours on it
JA: OK got it. Last thing — Marine Mechanics generally expect a deposit of about $26 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.

Hello my name is ***** ***** am I speaking with?

Would you please post the serial number on the engine?

How does the engine run other than the idle, does it make full power under a load?

Customer: replied 1 year ago.
1B254134. When I picked it up from the original owners boat house and ran around to the ramp. Under power it ran fine 52mph no skip under full throttle
Customer: replied 1 year ago.
Sorry my name is ray
Expert:  Jason replied 1 year ago.

Hi Ray. Can you describe what it is doing at idle? Is it misfiring and shaking?

Customer: replied 1 year ago.
It will run shaking and going dead about 30 secondsinto cranking. rpms r running up and the dropping then going dead. But it fires right up turn the key and it fires off
Expert:  Jason replied 1 year ago.

Hmmmm.... Lots of things can cause that. Old fouled spark plugs can do that. High fuel pressure could do that. And if there is a bad sensor on the engine that could do it as well. Have you done any kind of diagnostics on the engine?

Customer: replied 1 year ago.
Running the engine I pulled the plug wires off one and a time looking to see if there was any change. But its running to rough to notice any changes. And of course change the gas and put marine stabil in the gas. If u were me where would u start. Could it be a coil pack
Customer: replied 1 year ago.
What sensors should I change. The cheap ones first
Expert:  Jason replied 1 year ago.

To start, the engine would need the compression tested, spark output tested, and fuel pressure tested. Its also a good idea to run the engine off of a portable tank filled with brand new fuel to rule out any kind of fuel quality/bad gas issue. Are you able to do any of that?

Customer: replied 1 year ago.
I can't other than run it and change those plugs they were horrible and autolite plugs change them back to ngk
Expert:  Jason replied 1 year ago.

Fouled plugs would do it. So start with that and let me know what happens. Do you need the correct number for the plugs?

Customer: replied 1 year ago.
Jason thanks for ur help I changed the plugs but no luck. So I took the boat to my mechanicThanks
Expert:  Jason replied 1 year ago.

You are very welcome Ray. I do like to hear the outcomes, so if you don't mind, let me know what the final verdict ends up being.

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