Mercury, 40eojet30, 1999

by Myles
(Bainbridge PA)

Since last fall the engine loses power. Starts fine, idles fine, no misses. I power up and get on plane in about 30-45 seconds. All okay for about another 30 seconds and the the engine loses power while still in full throttle. The engine continues to seem to run fine but juat at a reduced speed of about half power or less.I replaced fuel filter, all gas lines including new gas tank. The fuel pump was rebuilt.All this done this year. Nothing has changed. Can anyone help?

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Jan 17, 2020
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starstarstarstarstar 		1998 Mercury Mariner 30hp
by: chad

I've got the same problem, I've replaced the fuel tank, fuel lines, fuel filter, rebuilt the fuel pump, cleaned the carb. Mine starts fine, idles fine, goes into gear and gets to about 1/4 to 1/2 throttle and dies out.
Oct 27, 2019
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starstarstarstarstar 		motor bogging out at higher speed
by: Sooner be sailing

I too have a bogging out issue. Merc 40 hrs 4-stroke made in late 90s, on a 16 foot Boston Whaler, has run beautifully for many years but this year it will start fine, idle fine, struggles but does run up to mid throttle and get the boat planing but more throttle and it starts to falter. If I leave throttle up it goes to complete stall. Feels like lack of fuel. Mechanics have cleaned the 3 carbs several times with a year. Problem getting worse. Fuel pump works fine, filter new, gas line clear. Ignition checked over by Merc mechanics, replaced one coil but barely needed it, plugs new.
Running out of money for this. Ideas welcome.

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