View Full Version : Carb needs adjusting, help please

05-04-2006, 10:29 AM
I've got a prostar 205 with the 285 HP engine and the engine seems to be running rich, to the point at times I can smell the gas when its running, and I notice the last time I was out I was behind the boat 5 feet or so and could smell it pretty good coming out the exhaust.

Questions are:

1. Whats the best way to adjust the carb. Friend of mine runs a mech shop but I can't exactly take a boat in there, so can I take it off and take it to him, or does it need to be running to tune good?

2. Whats the best/easiest way to clean one because it may just be that it needs a good cleaning.

Sorry I know very little about carbs, I'm a fuel injection guy so treat me like a novice here.

05-04-2006, 12:19 PM
It would help to know what carb you have on the motor. If it's a Holley they are quite easy to adjust.

Post back with the make and model of carb and someone will know for sure.


east tx skier
05-04-2006, 12:24 PM
If it's stock, it's a holley 4010 (dual feed). Apart from having extremely bad experiences with that carb, here's the mixture advice I've gotten from skidim. I'm not a mechanic, but this will give you something to read until someone more knowledgable shows up.

1. Rev up the engine to clear it out.
2. Turn air screw in until you hear engine begin to bog and miss.
3. Now, turn screw out with 1/2 increments until you hear that the engine is steady and running smoothly.
4. Repeat procedure on air screw on opposite side of the metering block.
Thatís it!

In the picture, that's not the screw that the dude has the tool on. That's just there for you to look at.

For "cleaning." Go to an auto part store and get a can of Sea Foam. Warm the boat up and slowly pour half the bottle into the throttle body of the carb. Kill the boat and let it sit for 20 minutes. Pour the rest of the bottle into the gas tank. After 20 minutes, crank it up, warm it up, and drive it like you stole it. Makes a nice smoke screen.

east tx skier
05-04-2006, 12:30 PM
I think this is where the screws are (general area).

05-04-2006, 02:14 PM
It would help to know what carb you have on the motor. If it's a Holley they are quite easy to adjust.

Post back with the make and model of carb and someone will know for sure.


Its bone stock so its a Holley. Sorry thought everyone would assume that.

05-04-2006, 03:02 PM
Your boat if your not the original owner could have the 4160 carb because so many 4110 are junk. The way you tell the difference is the color of the carb, if it is golden in color like eastie posted your in luck you have the 4160, if it is all aluminum and has 2 fuel lines going in the carb, go get a new 4160 and trash the 4110 IMHO

05-04-2006, 03:20 PM
If you want you can start with a 'bench' setting. Turn both mixture screws in all the way. Be careful turning them in, be gentle. Then turn them 1 1/2 turns out. The motor should run fairly well at that setting. Then follow Easties instructions above. Remember that the mixture screws only affect the mixture at idle. Once off idle they have no affect at all. There are a couple of other things you can check before you take the carb apart. Make sure that there is a small amount of clearance between the accelerator pump arm and the cam on the throttle (It's right where the cable attaches to the carb). There should be about a 10 thousands gap when the throttle is closed all the way. If there isn't then the shaking of the motor will cause the accelerator pump to 'piddle' fuel into the carb. If you find that the mixture screws are not effective (you should be able to stall the motor by screwing them in) then make sure that your secondary throttle plate is closed all the way and that the main throttle plate is covering the transfer slots. (manually move the throttle plates open and closed while looking down the carb, with the motor off, you'll see the slots I'm talking about)

If none of that works then you may have to take the carb apart and check the float level etc. Actually your carb may have the little sight windows so you can see the float level. Have you checked that?

There's a couple things to check anyway. Good luck and like I said, they Holley carbs are fairly easy to tune up.

There are several people on this board that know a lot more about carbs than I do. If you're having trouble sorting it out they will help you through it I'm sure.


Kevin 89MC
05-04-2006, 11:10 PM
www.holley.com is a great place to start. Lots o' info there . . .good luck.

05-05-2006, 07:41 AM
In the picture Eastie provided, "J" is the idle screw in the primary metering block - there are two, one on either side, there are none in the secondary metering block...

I still need to do some float level adjustments on mine - "A" is the screw that adjusts the float level, on the side opposite in this pic there is a screw on the side of the bowl you remove and adjust the float such that fuel is just at the bottom of that "sight port" - there is one of those for each bowl.