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95 fourwinns 351 omc while at a stop i hit the throttle half way and the boat ran good but when going to full throttle it hesitates then i pull back on the throttle and it runs back to normal? When going full throttle it starts to hesitate. .any ideas what it can be i just had the battery checked and its good??

First check your spark arrestor screen. If highly loaded up with crud, it can do this.

Is this a fuel injected or carbureted engine?

If it is carbureted, then a carburetor rebuild is probably overdue. Here is one simple test you can do to see if the engine is starving for fuel at the higher throttle setting:

While the engine is "hesitating", give the throttle 2-3 very quick pumps to try to pump in extra fuel with the accelerator pump (returning to the same higher throttle setting). If the engine "takes off" for 1-2 seconds, then returns to hesitating, then that confirms it was starving for fuel...Carburetor rebuild needed.

If your hesitation is only when hitting the throttle for fast acceleration, then that indicates a bad accelerator pump...also needing a carburetor rebuild. When replacing an accelerator pump, make sure to use the green one (silicone) which is ethanol tolerant.

Ray

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Hey Ray, thnx for the info my boat is fuel injection..i just got a fuel separator going to install it maybe that will help..but still open to suggestions..thnx for the info..

I would think that EFI for sure would have come with the normal water separating fuel filter.
You may need to get the injectors cleaned but always check the ignition system first before delving into EFI or carbs. Plugs, plug wires, cap & rotor.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

hey lou, yes it has a normal water/fuel separator filter I replaced it yesterday going to run it and see how it goes, what would you consider having the fuel injectors cleaned?? also check the ignition system where do I start??