I've been through the mill with this in my Coupe, it was a beach car run on unfiltered canola oil with no fuel cap until it died......
Anyway, I began using Startron, I bought it @ West marine and as mentioned it in an enzyme that eats the fungus so it is very fine and passes through your system instead of clogging the filters .
I also used K100 :
https://www.amazon.com/K-100-K100mg-Oz-Bottle-8oz/dp/B008Y2CH84/ref=sr_1_2?s=automotive&ie=UTF8&qid=1519054157&sr=1-2&keywords=k100+fuel+treatment
Works very well .
Be aware you may have to take the fuel sender apart and clean the fungus out of it as there are tiny little sediment traps designed inside the sender .
Get cracking on this before it's a huge problem .
I once got a tank of dino - diesel from Chevron that looked like
COFFEE ~ as mentioned they didn't care .