Needle and seat help

[SJD1974]

These are pictures of WH40 carb float, needle and seat area. This is a new needle and seat with no changes made to any of it. The wire i have circled in red is the point of this. Does the float control the lifting of the needle and pushing it down for fuel flow?
Is the float tab and the wire attached to the needle, what are used to lift the needle?
Or does fuel pressure lift the needle for fuel to flow until float reaches the point to shut off fuel flow.
My original ones fit so that any direction you moved the float it moved the needle in or out.

[rgsauger]

Fuel pressure forces fuel into the cavity in which the needle sits. The carburetor uses fuel from the bowl. As the fuel level drops in the bowl the float pulls the needle open to allow more fuel in. When the float raises up from the new volume of fuel in the bowl, it shuts off additional fuel. It works exactly like a float valve in the back of the toilet. When the water level drops, the valve opens to let more water in. When the water level gets full, the valve shuts off. It is the exact same thing in the carburetor.

[rgsauger]

If you have not downloaded a manual for your motor, spend a little bit of time digging around and you will find one. It is critical to have a factory service manual for your motor for everything that you are doing.

[SJD1974]

I just didn't know if there would be enough fuel pressure to open it. I am diesel mechanic along with a lot of other things and have worked with similar valve that pressure would open it and the float would close it by pushing the needle down as it raised in the bowl plus it surprises me that i have to alter a new needle and seat. If you look at the picture you will see that the float can not possible lift the needle, that picture is with the float adjust to its 1/16th and when the float is at the bottom of the bowl it does not lift the needle at all. So thats why i will have to modify the wire that is being used to lift the needle.
This is where i got part number https://www.marineengine.com/parts/m...0412BD/299_110
from wholesale marine.
The old needle and seat work as you describe but they were worn out. Hence the reason to by new.

[SJD1974]

Here is a better picture where you can see the needle with the wire not even touching the tab on the float and the float is down in the bottom of the bowl as if there was no gas in the bowl.
Attachment 499531

[rgsauger]

Read the manual. You gotta flip it upside down to set it.

[SJD1974]

I did it just like the picture

[Dave Strong]

Fuel pressure has nothing to do with it, when fuel level in bowl gets high enough, to preset height it shuts fuel off. When level drops the needle comes off seat and lets fuel in until level comes up and needle closes seat.

Dave

[Chaz]

Take your old needle .. pull the wire off and throw it away.

Now set the float be throwing the carb top against the wall.

Assemble the carb, hook a fuel line to it that has aprox 5 psi of positive pressure, give or take +/- 1 psi either way.

Start the boat, run it across the largest waves / wakes you can find.

When the needle tries to fall out of the seat, gets stuck half open, fills the cowling with fuel and that split plug wire boot starts a catastrophic fire ... be sure you put the fire out so you can do a forensic analysis of what went wrong. As well as come up with a fix for the problem.
I would imagine you would find that if you added a little wire that did nothing except in a rare instance of stopping over travel like when a carb is empty, full float drop, and wedged needle.
The advanced fix is to lightly tap on the side of the carb body with a wooden mallet or screwdriver handle as the carb is filling .. not in the book and in this day and age, seems to be somewhat of a lost art.
For those with ADD or ADHD , designing a float arm that is radiused to follow the fulcrum point could 'in theory" put a small rollerized wheel on each side of the wire to precisely control arm movement in both opening and closing events.
The downside would still be that gravity and pressure are the critical influencers in the equation..

If none of these thought's and general practices make sense, go back and re~read RG's parable to the basic crapper valve ..

[OnPad]

I had a fire like that last year! My fuel fitting came loose. The one right next to the schrader to test fuel pressure on a 95xri. Broke the braze, solder or glue or whatever they used. Luckily I had a good fire extinguisher and didn't have to call in the forensic team.

[tlwjkw]

if you followed tha book you'll be fine... thats correct for all wh series carbs.

[Merc 2.5]

Fuel pressure has nothing to do with it, when fuel level in bowl gets high enough, to preset height it shuts fuel off. When level drops the needle comes off seat and lets fuel in until level comes up and needle closes seat.

Dave

Exactly.dave

O.p Somewhere u said the needle dont move , so 1st thing 1st , is clean piss out of everything and every orifice, when needle moves freely then it will open and shut like norm , floats set 16th below bowl surface, I've also seen some leak at 16th 8th will work fine

[OnPad]

O.P. should have posted this.

[SJD1974]

That picture tells it all. Needle was not moving to the open position due to the wire spacing as seen in the picture. I have taken care of the issue. They are new needle and seat, so nothing is sticking.
I should have posted that picture.

[Glastron1987]

I try testing mine for just basic function (not actual adjustment) by first blowing (by mouth not compressor) into the carb inlet while right-side-up with the float hanging. It should allow air in. Then I turn in up-side-down and at try to blow air through, and it should be blocked in this position.