Whats a vent jet do

" I have a mercury 150 hp v-6

" I have a mercury 150 hp v-6 and problem with low end power, its got great top end at around 6200 rpm and with no skier its fine, maybe alittle slow on take off, but when I got a heavy skier on slolom, it floods out on take off, once I let go the boat is gone. its got 120lbs. compression in all cylinders. good spark but the plugs always look damp, eliminated oil gas mixture, and reeds they all looked good, but I was going thru a carb and seen that the book says its suppose to have .080 main jet and .092 vent jet, but Ive got .080 main jet and a .078 vent, I cannot even find a motor listed that would have a .078 vent jet. So would this cause a rich fuel/air mixture? The carb is a WH 40 the motor is a 1988 mercury xr2 150 hp v6. apreciate some advise. Thanks: "

" I see you're still havin

" I see you're still having problems with that engine. The vent jet restricts the amount of air or venting to the fuel bowl. As you accelerate and use more fuel, the vent smaller vent jet lets in less air to restrict the fuel flow. It's like having an airtight container with water in it, adding a straw to a tight hole to suck the water out. The straw would be difficult to suck on. Now punch another small hole into the lid. The water would flow easier. Make that hole larger and the flow gets even easier. That is how the vent jet works. So with a smaller vent jet you would get less flow and a larger one would give more. This system is mainly used as an economy measure for the transition between low and high speed operation, so that when you mash the throttle hard, you don't get a large surge of fuel due to the sudden vacuum created in the carbs venturi. It sort of creates a drag on the fuel flow. I hope I have not totally confused you- if so, maybe someone else can shed more light on this subject.
Tom "

"Dave,


Tom's explanat

"Dave,


Tom's explanation is right on the money in my opinion. When I read these messages I recalled looking into the recommendations regarding these vent jets. While the manufacturer does advise certain configurations for each engine, and variations that may be tried, they also mention that experimenting with different jets is a good idea. They go even further and say that you might find using different jets based on the position of the individual carb, may prove helpful; the lower carbs may use a different jet than the upper carb.

I will try to fing the service bullletin that deals with this and post it here later.

"

" Thanks Tom and Tony the way

" Thanks Tom and Tony the way it sounds it is not what I wanted to hear, for if anything it would be lean instead of rich. Boy this thing is really driving me nuts. I did set the floats alittle lower so when the carbs are on a steep angle at take off they would not flood the engine and it seemed to help some as far as sounding like flooding out is conserned,but if there is not someone sitting on the front of the boat it will just drag me around. I tryed to trim the motor to the next bolt and it seems to suck air. "