FXSTC has been sitting for a year. Started and spewed oil from the breather. Read all of the related posts in this and other forums and did the following:
Emptied the Sump
Rebuilt the oil pump
Replaced filter and all of the hoses
Confirmed routing of hoses correct and no kinks or blockage
Filled the tank a half quart low
Started up and oil again spewed from the breather. Emptied the tank completely. Refilled after again draining the sump and restarted. Opened the tank plug and oil is returning. Seems pressure quite high. Check valve and relief valve replaced on the pump rebuild and look fine. Bike has only 5,000 original miles on it. Any idea what could cause this? Could a vent be plugged somewhere causing too much pressure, perhaps in the rocker top?

 

Sounds like you're sumping. This is from a faulty check valve which allows oil to drain out of the tank into the crankcase. This is also not uncommon after the bike sits for a long time as some oil will leak past a good check valve over a long period of time.

 

As noted, rebuilt the pump including the check valve. Entire tank emptied AFTER draining the sump. Thanks for the comment though.

 

Can anyone help me with this problem?
Thanks
s

 

Armchair troubleshooting, but I would guess a something internal is cracked. Sounds like you have checked all the usual suspects. Time to look at the weird. If you can figure out how to pressurize the system without it running, maybe you can isolate it that way. Good luck.