Stumbling motor on acceleration

[girraf]

I noticed pulling skiers last week that my boat suddenly started to stumble around 1500-2000 rpm pulling a skier out of the water. After a 2-3 seconds it works its way through it and then settles out just fine. Other than maybe an accelerator pump, are there any easy adjustments I might be able to make on the carb that would help fix that problem? The boat will otherwise cruise at any rpm in a steady state condition quite nicely. Its just that initial acceleration is hiccups a little bit.

Motor is VP 5.7L 2bbl holley carb driving a cobra SX with 4 blade solas amita prop

I did just replace the thermostat and the engine runs closer to 150-160 now instead of 120. Wouldn't think that's having a negative impact but thought I'd mention it.

 

[insttech1]

Basic carb tuning principles should generally apply. How long since rebuild? Fuel filter? General tuneup? (plugs, rotor cap, rebuild kit, adjustments, etc...). Check carb float level for correct settings. There are two ports on carb to achieve best vacuum pull and easily checked w/ cheap harbor freight vacuum gauge kit. A holley (assuming holley 2bbl) rebuild kit comes w/ full tuning instructions. Search the forums here for "carb", "tuning", "carburetor", "tuneup", etc...and you should get a ton of info on what to address. There is probably much info in the stick post "adults only" section too. I went through the stutter myself and got it 90% fixed, but in my case, I also need a new baseplate as my butterflies are a little "off".

 

[Scott Danforth]

you cant adjust a bad accelerator pump or crud in the fuel system.

check the contents of the fuel filter (and replace the filter). if the contents are anything other than good clean and pure gas, drain and clean your tank.

if your accelerator pump circuit is plugged, your carb has to come apart to clean. (no magic mechanic in a can will ever work)

 

[Insomnium]

I had a tiny leak in my accelerator pump and had similar issues a while back. It was sucking air and slightly leaking. Easy fix thankfully. If you are not sure when the carb was last rebuilt, may as well do it. You could have gaskets on their way out and crud in your jets and such.

 

[Augoose]

Can the skier hear any "popping" sound from the exhaust during the hole shot?

 

[girraf]

Can't notice anything when your skiing. If you know it's happening you can feel the pull lighten up just slightly but otherwise it's not apparent when you getting up out of the water.

 

[Bondo]

Can't notice anything when your skiing. If you know it's happening you can feel the pull lighten up just slightly but otherwise it's not apparent when you getting up out of the water.

Ayuh,... It's still a carb problem that oughta be fixed,....