There are basically two alternate methods for curing a crudded up tank.

The slow method, by using biocides and tank cleaner type chemicals, entails frequent and numerous filter changes. If your tank interior is really bad, this can take a year, in which case it ends up being pretty expensive. Burning B99 for a while can speed the process up.

The quicker method is to have the tank cleaned, and flush the fuel lines. It's also a good time to replace all of the rubber fuel hoses if that hasn't been done recently. After that, an occasional maintenance dose of chemicals, or continuous use of bio-diesel, should keep things clean as long as you are careful about where you buy fuel.

I've never had to have a tank cleaned by the second method, but I probably would if the situation were bad enough that I couldn't keep ahead of the problem with filter changes.

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'79 240D

Ya, sounds like plugged filters to me too. Good news is that's not hard to fix How's the clear pre-filter look?

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

The only time I actually had problems with crud in the tank, I dumped some Startron in and let it sit for a day or so. I never did clean the tank.

Startron was the 1st response to my query. I was skeptical but car is still running. Just approximate the amount on the label.

West Marine carries it. The McParts stores have the gas version. There may not be any real difference between gas & diesel versions but go look on Startron's web site to be sure.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.