Carbs not taking fuel after reassmbly

My VM26SS carbs on my '76 Kz900-A4 are not taking any fuel from the fuel lines after I put them back together. I am really struggling with this as eveything looks to be okay. I have removed the float needle seat and flushed the gunk from the fuel input to make sure there wasn't a blockage. With the float bowls removed there is fuel that comes through the float needle as I allow the float to fall.

Has anyone else experienced this? Any suggestions on what to check next? I haven't made any changes to the tang on the floats themselves, but I can't be positive that the floats are back in the same carb they came from. Is it possible that the fuel level adjustment is too high preventing the floats from allowing fuel through?

I'm feeling pretty stumped on this one.

If you're not certain that the floats are back in their origional locations then they probably arn't.
You could check fuel levels in each carb to start with,should be done anyway I'd say.
For all 4 to how same problem suggests something common to all 4.

are you running a vacuum or a gravity fuel tap? perhaps your problem is the vacuum line for the petcock.if you are running a vacuum tap,have you tried the prime position?
the petcock wont flow in the on/res position without eng vacuum.

DoubleDub wrote:

My VM26SS carbs on my '76 Kz900-A4 are not taking any fuel from the fuel lines after I put them back together. I am really struggling with this as eveything looks to be okay. I have removed the float needle seat and flushed the gunk from the fuel input to make sure there wasn't a blockage. With the float bowls removed there is fuel that comes through the float needle as I allow the float to fall... haven't made any changes to the tang on the floats themselves... feeling pretty stumped on this one.

Just a shot in the dark, but am wondering if it's possible to install the floats upside down when re-assembling these carbs (with tangs pressing against the float needles)??

If not already done, might also want to assure the float bowl vents and vent tubes are clear and unobstructed (needed to allow fuel flow into the bowls).

Good Luck!

I have a replacement petcock from Z1E that is pretty much identical to the original gravity fed petcock of the Kz900A4. I'm pretty sure it has something to do with the floats since opening up the drain screw on the float bowl doesn't allow any fuel to come through. I had thought for a minute or so that the vent was blocked.

DoubleDub wrote:

... I'm pretty sure it has something to do with the floats since opening up the drain screw on the float bowl doesn't allow any fuel to come through. I had thought for a minute or so that the vent was blocked.

Yes --- removing drain screw should allow fuel flow even with a blocked vent (unless the drain hole is also clogged).

Good Luck!

I tried to clean out the float seat with a greeny from the kitchen and was able to remove some gunk - they all look to be pretty clean at this point. Is there any kind of coating on the float needles that is removed over time that allows them to slide against the float seat? Would new needles be "slippery-er"?

DoubleDub wrote:

... can't be positive that the floats are back in the same carb they came from. Is it possible that the fuel level adjustment is too high preventing the floats from allowing fuel through?... Is there any kind of coating on the float needles that is removed over time that allows them to slide against the float seat....

can't be positive that the floats are back in the same carb they came from --- not the best practice, but don't believe it's a critical factor in the current fuel flow problem.

Is it possible that the fuel level adjustment is too high --- not highly suspicious of that because of haven't made any changes to the tang on the floats themselves.

With the float bowls removed there is fuel that comes through the float needle as I allow the float to fall --- this indicates that fuel is in fact flowing through the seat as it is supposed to do when the float needle pointed tip is not being pressed into the seat orifice by the tang pushing against the needle base.

I would concur that there is something amiss regarding fitment and free movement of the float within the bowl, which is preventing the tang from pulling away from the float needle while the bowl is attached. In other words, something inside the bowl is rubbing or hitting the float and mechanically preventing the float from free-falling when only its buoyancy is supposed to keep it from free-falling. (That's why previously mentioned any remote possibility of having installed the floats upside down).

any kind of coating on the float needles that is removed over time that allows them to slide against the float seat --- don't think it is a factor here.

Question --- are the float needles damaged in any way? Such as the tiny springs in the blunt end where the tang pushes against having gotten stretched out so that the needle always stays pressed into the seat orifice? Or any possibility that the needles have rubber points which might have gotten swollen or softened by carb cleaner.

Question --- are the parts involved all the same floats, needles and seats that were interfacing correctly and properly functioning BEFORE the carbs were disassembled, cleaned and reassembled?

It is perplexing because this problem of "no fuel flow" is so opposite of the usual issue of a float needle still persistently leaking after cleaning and reassembly.

Good Luck!

After all that -- is there plenty of gas in the fuel tank? :laugh:

I'll verify the float installation. I believe I have the tab on the top which seemed correct (should prevent movement upwards, but not downwards). In fact, I know this is the case as the floats will drop far enough for the float needle to fall out partially if I don't put the bowls back on. But again, I'll verify.

The floats all look to be in good shape - the springy pointy end operates as I assume it should. It is possible that the rubber tips have softened - I can't say myself for certain.

All parts are the originals from when the floats were disassembled (I guess I should be more clear - I didn't disconnect all the carbs from the holder or make any changes/disassembly of the slides, main jet needle, etc).

Oh - and the tank is about 2/3 full.

I think you're onto something with the rubber head on the float needle. I did some checking using a funnel and hose on one side of the carbs. I laid them on their face so that I could access one float bowl. I removed the bowl and the float/float pin and put some fuel in the funnel. The fuel still sat in the hose at the intake. I used a pair of needle nose to gently tug on the float and fuel started to come out.

Is it common for carb cleaner to expand the rubber tips? I have been running a good amount of sea-foam in the tank as I try to get it running again this year.

I'll go ahead and order a new set of needles, is a new seat recommended as well?

76 VM26SS or VM26SC float needles shouldn't have rubber tips.