I have a 2003 Four Winns Horizon with a 5.0 GXI. Engine fires up and idles great, but when I try to go above about 3/4 throttle it starts to miss. No backfire...just quick misses at high RPM. I can punch it full throttle to get it up on plain and she jumps out of the water with no hesitation like a champ. Once it gets on plain and gets up to speed it will start to miss...but only if I try to go past about 4000 RPM...anything less and it runs great.
New plugs and OEM plug wires this month along with distributor cap and rotor...No difference when changed.
New fuel pump in July of 2015.
New fuel filter at twice so far this season....no change in performance...been through a few tanks of gas so gas is fresh...and I have used ethonal free fuel as much as possible this season.
Fresh oil all around at beginning of season...new impeller last season.
Temp is good, oil pressure is good..
Anything else I should be looking at?
I have not changed the fuel lines, but that job requires removing the whole back seat and some other things so that will be an off season job.
New plugs and OEM plug wires this month along with distributor cap and rotor...No difference when changed.
New fuel pump in July of 2015.
New fuel filter at twice so far this season....no change in performance...been through a few tanks of gas so gas is fresh...and I have used ethonal free fuel as much as possible this season.
Fresh oil all around at beginning of season...new impeller last season.
Temp is good, oil pressure is good..
Anything else I should be looking at?
I have not changed the fuel lines, but that job requires removing the whole back seat and some other things so that will be an off season job.