[Vwdiesel] white smoke

[jeremy]

My 81 Rabbit pu always starts right up but with a puff of white smoke out of pipe. It would run for few seconds smoothly without white smoke then a lot of white smoke returns with engine running rough before it dies. Depressing the accelerator doesn't seem to do anything to the rpm. It does this start after start. The engine will run only about 10 seconds each time. The clear rubber fuel line from filter to IP shows no air, the filter is brand new. Any idea what is not right? 
Thanks.Jeremy