The usual setup found on most diesel
engines is a primary filter of 30 micron and a secondary of 10 micron.
Because my fuel and tanks are clean and I buy clean fuel, I run a 2 micron primary and my 10 micron secondaries never get dirty. But because filters also trap water
, I change them yearly. And my tanks were built in 1942.
could be your problem if the problem is ongoing. Make sure your fill and vents can't allow water into the tank. Use a good fuel conditioner. One that absorbs water (so it will burn with the fuel) and includes a biocide. Keep your tanks full when sitting so it's harder for condensation
The additives I use are Algae-x and Archoil 6200.