Tank won't feed gas if fuel line is connected

Finally got my carbs working properly (thanks to many quality parts from XJ4EVER). While I was checking the fuel bowl levels, I had the tank off to the side and was feeding fuel through and extended auxiliary line. I had no issues during this process keeping the line full.

After that I had disconnected the aux line while I hooked up the synch gauges, and later hooked it back up to continue the synch and idle adjustments. At this point, the line was having trouble getting fuel from the tank, but if I moved it a bit up and down etc to work the bubbles/air I could get fuel down the line, but it didn't seem to be flowing freely.

I was able to successfully get the carbs running correctly, and then began the process to get the tank back on and hooked up properly. What I noticed then is that there was no fuel flowing from the tank, with the petcock in any postion ( I know this for certain because I have a in-line filter so I can see flow).

The vacuum line did open the valve in the ON postion, I noticed this because I forgot to tighten the clamp on the line and I had leakage at the outlet, but after tightening and trying again still nothing.

If I remove the line I will get plenty of flow from the petcock in the PRIME setting, but immediately after hooking it back up nothing will flow through the line.

Any ideas here? I'm so lost on this one...

 

I know my taps have a rubber washer/plate in them.
When you turn the lever it directs to one of the holes in that washer.
I have had this washer mangled also and it didn't work so well.
I recently purchased a complete tap from len because it drove mad.
In saying all of that.
Pull the tap apart and have a squiz.

 

It's probably working just fine. IF you have fuel flowing out on prime when it's disconnected and when in the on position with vacuum (you said you had a leak) then it is most likely working on the bike as well. Very little fuel flows into the carbs when running and there is always an air bubble because of the lines position. All my bikes the filter is horizontal and the filters look empty. When you use an aux tank and hang it up the filter is vertical and the air has somwhere to go.

Big question.....does it run when you have the tank on? If so, you're probably good.

 

yep /\/\/\/\ what jayrodoh says , it appears there is an air-lock because the float valves are shutting off the fuel flow, as the fuel bowls begin to empty , fuel will flow, but it will be very slight whilst running

 

Makes sense, that was kind of what I was thinking at first as well. The only problem is that it did shut off after it seemed to have used up what was left in the bowls, and still wasn't allowing any fuel in.

Thinking I might try draining the float bowls completely and see if I can get the system to re-prime after that.

 

I'm pretty hesitant to blame the petcock on this, because
A: it's actually brand new itself, but also
B: it works 100% as intended without the fuel line hooked up, so I'm led to believe the issue is further downstream

 

Seems to have worked. Still much less flow than I would have expected, not enough to even fill the filter (horizontal configuration) to the point of the line exit, but I'm thinking that must be enough that it's getting through by capillary action or something... But I took it for a short test ride and it seems to be fine other than needing some additional fine tuning on the carbs.

Alongside the same topic, what are you guys using successfully for filters? Currently I just cobbled together what I could make out of generic AutoZone universal hardware, but it's far from an elegant solution. Is there anything that fits nicely in that tight space?

 

Something like this:
Tusk In-Line Fuel Filter

 

Chacal has one like that with a right angle. Fits perfect in the space. I quit buying stuff like that on Amazon and eBay……it’s a crap shoot if you’re getting quality stuff or the cheap crap. I’ve had filters and vents melt because of fuel. Had a golf cart leave me stranded in the woods because of it. Was 3AM and beer was involved but that’s another story…….

 

Oh, yeah that looks more appropriate. The conical design would definitely help fit over the carb hats better.

...but that sounds even better! I'll have to have a look.

 

I meant to respond to this earlier, wouldn't be the first time we've had a member where the float/needle stuck in a carb after a rebuild. It'll usually sort itself out after a little runtime.