carb rebuild-no fuel

[shepgs850]

just rebuilt the carbs on my gs850 trike with individual k&n filters also been rejetted
reset the mixture screws at 2 1/2 turns out adjusted the floats to manual spec
fitted to the engine i can't get no fuel to any of the carbs unless i take the filters off put my hand over the outlets one at a time and push the starter button,this causes some suction and fuel the comes out of the outlets when i have done this on all four carbs the engine will start no problem
leave the engine running for 10 mins was ok,a couple of backfires
turn the engine off,try to restart NO FUEL!!!! any one got any ideas

[Nessism]

Possible reasons: petcock is not opening, fuel line is kinked, filter is plugged. Did you relocate the fuel tank to build the trike? If so, maybe the fuel outlet is below carb level?

[shepgs850]

all the possible reasons for the previous post are ok
thanks any way any one else with any ideas?

[Nessism]

Questions: if you take the fuel line off the petcock and turn the petcock lever to "prime" does fuel flow? Is there any gas in the float bowls when the problem occurs?

[shepgs850]

right,the carbs are now gravity fed not vacuum assisted blanked off the vacumme pipe on carb 2(no leaks there at all),have 2 petcocks(because the tank has 2 a custom mustang tank) both have just on/off positions
carbs were working befor i gave them a service

[shepgs850]

sorry, yes there is fuel in the bowls when the problem occurs

[Nessism]

If there is fuel in the float bowls when the problem occurs the only thing I can think of is a mixture issue or maybe a vacuum leak. If fuel was having a hard time getting to the carbs I'd look at your tank vent and/or custom tank configuration so see if there is any fuel delivery issues.

[shepgs850]

mixture problem you think,do you reckon its worth re-doing the 4 mixture screws perhaps trying to start the engine on every quarter turn?and when it does start and idles ok give the carbs a balance?fuel to the carbs doesn't seem to be a problem but i will still keep an eye on it just in case cheers

[Guest]

Make sure the vent lines are clear. They come off the other two T connections connecting the carbs. They need two free flowing lines with air to breath or the float bowls won't flow in fuel.