Just judging from the photo, my gut feeling is that it's scooping up too much air.
Is the spray bar "keyed" for proper orientation...?
I've never come up with a sure fire way to test the pipe seal, but it seems that for peace of mind an external seal could be added for peace of mind. If you melt out the seal during a hot run, there goes the engine. It's just like leaning out a cutting torch.