Chaps, there is some very useful information in this post which may be of help:

http://www.talkmorgan.com/ubbthreads.php/topics/129195/Petrol_Filling_Issues#Post129195

My filler also tends to "burp" fuel onto the back panel if it try to fill it too fast or too full. So, I'm going to check my filler vent line and if necessary modify it in accordance with the suggestion to maintain an upward sweep.

P.S. Apologies in advance if I've got my "threads crossed", so to speak, as the original post is on the M3W area.

Philip.