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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have twin 2001 mercury 250 efi outboards they start run great

Customer Question

I have twin 2001 mercury 250 efi outboards they start run great when you are in the water idleing they are fine once you get out and go to throttle up they bog and will not go over 1800 rpm but if I neutral the motors and throttle them up they will slowly get up to higher rpms once it gets to about 4000rpm it is like they clear out and rev no problem then I can put it in gear and the boat takes off no problem and runs great 6000rpm I have replaced spark plugs (champion ql77cc gap 35) both fuel pumps are new all new injectors I am at a loss any suggestions
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
also did fuel filters
Expert:  Charles replied 1 year ago.
Hello, my name is***** you for allowing me to assist you today.
Does both engines behave the same way?
would you please post the serial number from one of the engines?
Customer: replied 1 year ago.
yes they do the left one more than the right one but both do serial# ***** (###) ###-####xlefi
Expert:  Charles replied 1 year ago.
Have you done a compression test on the engines yet?
Customer: replied 1 year ago.
yes the lowest one was at 120psi but all where 128 or better
Expert:  Charles replied 1 year ago.
OK, that is really good.
Are the engines rather smokey at first start, maybe even hard to start?
Can you remove one of the gear cases to check on an issue with the early 3.0L engines?
Customer: replied 1 year ago.
they fire right up yes they smoke a little and yes I can remove a gear case if need be
Expert:  Charles replied 1 year ago.
I would like for you to remove the case from the engine that is running the worst. You would then look up at the exhaust ports in the exhaust pipe. See if they are plugged with carbon.
What kind of oil do you use?

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