what engine?
anyhow for tdi what wrong with standard mechanical pump?
Post pump will draw air in through the standard fuel filter nipple instead of expelling it when it comes to priming the system so you can no longer do that. As part of veg oil conversion my mechanical is re-plumbed as post pump via choice of two filters. It has not been a problem yet as the system is largely self priming but if it become issue air would have to be released at the Injection pump union.
why not an proper diesel inline gauze pre filter to protect leccy pump installed near the tank pick up and then a post standard filter before the IP.
