I did this twice, the spin on filter should be full of something before you put it on. If you do this to a 603 it does not want to start, if you ever run a 603 dry good luck I hope you have AAA.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

In addition to the things you already did to fix the air..., you might have old, original rubber fuel lines that cracked inside when you changed the filters. These can allow air into the system too.
Also, don't underestimate how much crap might be in your tank/fuel system too; the biodiesel will devour it all, and send it to whatever screen/filter is downstream... so carry a few extra filters.
new bosch upgraded primer pump is like $15, but I've heard anecdotes regarding it's unsuitability for biodiesel.
cheers,
Kevin

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Cannondale ST600 XL
Redline Monocog 29er
2011 Mini Cooper Clubman
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