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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 a 2005 Mercury 40 HP EFI Big Foot 4 stroke ser #1B099527

Customer Question

I have a 2005 Mercury 40 HP EFI Big Foot 4 stroke ser #1B099527 Mod#40ELPTEFI runs excellent in neutral full RPM range. When under load only run up to about 3000 RPM then begins to die out bring it back down to about 2800 RPM and runs fine for hours always starts right up and idles good. Fuel filters are good all hoses are good, replaced plugs, dis assembled both fuel pumps no varnish or break down of diaphragm, seals, or o rings. Fuel pump outlet pressure is a steady 40/42 PSI even when it starts to die out. Flushed fuel system, new premium fuel. What to do next?
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
Two days no reply??
Expert:  Charles replied 1 year ago.
Hello, my name is***** you for allowing me to assist you today.
I have been thinking on your problem. When you changed the filters, did you replace both the low and the high pressure filter?
Which spark plug do you have in the engine?
How is the oil level?
does the alarm in the boat work?
Customer: replied 1 year ago.
Both filters plugs were champions they looked good I put in nkg I do not know if the alarm Work I have never heard it I bought this new. oil level is good and has a good stream of water when running. motor runs like a champ in the yard.
Expert:  Charles replied 1 year ago.
Ok,
This engine calls for the Champion plug. It may not run well on another.
Take the thermostat out of the exhaust plate and test it in hot water. Make sure that it is not stuck open, and that it will actually open when it gets hot.

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