What is the difference in these 2 mikuni fuel pumps? One fs 49 carb going lean ?

[masterblaster]

I checked pop off and pulled jets everything seems normal but front carb keeps going lean even with adjuster screws further out than rear Cylinder.
Pulled fuel pump and seems like there is a good bit of range motion on the clear diaphragm compared to another spare I had around. The whole pump looks different. Does a new clear diaphragm that moves less give better fuel flow

 

[Big Kahuna]

Second picture, is one of those the back view and other front view?

 

[masterblaster]

No air leaks and the second pic is same side of pump. One is a gold fs pump the other is a black one. Not sure the difference But the clear diaphragm is glued on the gold one and has much more motion in it. The black one seems to have thicker clear diaphragm that seperates from it Not sure if the gold one is worn out ?

 

[masterblaster]

Here is other side of the black pump

 

[Ducky]

Is one more of a "slave carb"? The one doesnt seem to have a pulse fitting?

 

[Big Kahuna]

Looking at the valve holes they look to be different pumps, dont know if this could be causing some variance.

 

[tomski]

 

[Storbeck]

The rubber things are in backwards on the bottom one. I suppose as long as they are holding the check valves in and the check valves are functioning properly it wouldn't matter, but there is that. Also it's interesting that the "ports" for the check valves are not the same, I can't see how it would matter, but still kind of interesting.

 

[masterblaster]

U can see the gold pumps are both currently on the full spec carbs. I was just contemplating using the lower black one to see if it was a fuel pressure or pump issue. The black one has a pass through between the check valves also.
both have pulse lines of course they are shown in the first pic
How many carbs have the clear plastic diaphragm sealed to the block. Do these wear out or get to much range of motion in them ?

 

[Storbeck]

Swap the pump between the carbs, if problem follows the pump then you know to look there.

 

[masterblaster]

I was thinking about doing that but I don’t really Wana have to do it twice. Just as well fix it first time. Called Ed left mesg about it

 

[Jcary85]

Are the bottom check valves on the same sides? Almost looks like the bottom picture is on the back side but hard to tell.

 

[masterblaster]

Talked to Ed at fs. He says fuel pump diaphragms rarely wear out and are suppose to move this far. Also the black pump is different because it came as oe on some yami or kawi spec ski. Mikuni direct are made to diff specs. I must have a small air leak somewhere that I just havnt been able to find