sand blaster advice for working on my 60 stepper

[smilts60]

I tried asking in paint and body no reply. But I bought this blaster kit http://www.ebay.com/itm/170693975294...84.m1439.l2649

got it and some fine black beauty blast sand. Problem Im havibng is it sprays for about 2 seconds then stops. I can let off of the trigger and re pull it and get another 2 seconds over and over but it wont keep a continuous spray. Ive tried the putting the pickup tube in the top of a bucket, and near the bottom sideways.