I know that this topic has been widely discussed but I am going to ask anyway. Please forgive the redundancy!

I have 6-71 N's JT modified with duel racor primaries and canister mounted element filters for the secondaries. My boat came with a fuel priming pump mounted between the racors and the secondaries. Both engines fire right up and run great.

My first question; I know that I can put new filters in both the primary and secondary filters DRY and then prime the system with fuel using the priming pump. What happens to all that air? Does it have to be bled and if so from where?

My second question; The owners manual for my engine (last revision 2004) specifies a P550540 filter element for the secondary filter. I looked up the specs on this filter and it is rated as a 22 micron filter at 99% efficiency. My understanding is that Detroit Diesels specify 30 microns primary and 10 microns on the secondary. Thoughts please. Thank you!


Jon