Had some serious trouble with this - combination of fuel filter issues and pick up/level senders being blocked

https://fuguttycars.wordpress.com/2015/11/22/winter-fleet-update-aka-dont-buy-old-cars/

fuel filters block quickly after switching to veg, but once switched maybe every 5-8k. If you have a blocked sender then maybe its low quality oil with lots of fat?

oh and this time of year if you are using oil that was filtered on warmer days then the fats will solidify, might be worth re filtering now its cold. But oils filtered in winter and used in summer are really nice to use.