Another FF change done wrong. Always remove the old diesel. You can't see anything smaller than 25 micro with the eye so you don't know what is in it. One drop of water will ruin your day. I'm 62 years old and grew up on a ranch. Been around diesels my whole life. It is up most essential that the engine gets clean diesel. I have seen more problems because of dirty fuel than any other single thing.
There’s a water separator in the diesel fuel system that collects water, and water is denser than diesel so sinks (water is not present in the fuel filter housing as it is high up).
