Sounds like you have lost fuel pressure to the filter. The inline filter is at a higher level than your pickup so the system needs to have pressure to hold fuel in the filter. You can get pressure back one of two ways. You can go get a small syphon kit from wal-mart for about $20. Then there is the old way of sucking the air out of the lines until you get a mouth full of fuel. When fuel starts to flow freely through the line again, plug it back into the carbs and go. If you let pressure fall again in the line you will have to get pressure back again, so keep your finger over the end of the hose to make sure this doesn't happen again.
Tampaski, June 2009