i wouldnt think so as a anti syphon device stops the fuel coming out not going in.?if your filling the van all the time? i supose it could be in the same garage mayb ur local? ive noticed for some reason pumps nowadays seem to be real slow? mayb this could be the problem, srry i couldnt really help, mayb some will leave another reply here so check back in time.
im no expert i just drive a vectra
vectrahed, January 2009