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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3341
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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2007 wave runner fx1000. Fouls #4 plug. Swapped coil sticks,

Customer Question

2007 wave runner fx1000. Fouls #4 plug. Swapped coil sticks, no change. Swapped #3 & #4 injectors, still too rich on #4. Runs so rich it delutes oil. Any other possibilities other than ecu? It cost $1400
Submitted: 1 year ago.
Category: Boat
Expert:  TIMOTO replied 1 year ago.
Check the compression on all four cylinders. When doing so hold the throttle wide open. Let me know what number
Expert:  TIMOTO replied 1 year ago.
Check the compression on all four cylinders. When doing so hold the throttle wide open. Let me know what number
Customer: replied 1 year ago.
Compression is 175 on all 4 cylinders. I have eliminated coil sticks and fuel injector as cause . #4 cylinder is getting a whole lot of fuel. My question was is there any other cause to flood this cylinder other than the ecu. It will run max rpm(10200) but at idle and cruize its flooding this cylinder. Owner has been changing this spark plug frequently and while doing so has deluted the oil to the point that it was over 2 qt over full, which I have changed
Expert:  TIMOTO replied 1 year ago.
I suspected that you had low compression on that cylinder but you numbers are good. Since I have not seen that specific problem before I will opt out and perhaps another expert has a solution for you.
Expert:  Charles replied 1 year ago.
Hello, my name is***** you for allowing me to assist you today.
Replace the t-stat on the engine. If it is hanging open the ECU will think the engine is cold all the time. Thus over fueling it. It could be a bad temp sender. Either one will lead to this.
Customer: replied 1 year ago.
I can't agree that a bad thermostat or Temp sensor would make rich condition in #4 cylinder only.
Expert:  Charles replied 1 year ago.
It could be one of these simple items or the injector driver in the ECU has failed.
Customer: replied 1 year ago.
So you think the t stat or temp sensor would create rich condition in #4 cylinder and not the other 3. I'll just thank you at this point and leave it at that
Expert:  Charles replied 1 year ago.
I am saying that you have ruled out most items already. Might as well rule that out too. Also do a leakdown test on the engine. It could be way off on that one cylinder.

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