He said the car is an '85 TD, so it's a wagon, right?

If it is a wagon, and it is anything like an '84 300TD, then the tank is super easy to drain.

If you have more than about 5 gallons of fuel in the tank try pumping most of it out through the filler hole.

Back the rear wheels up on ramps or jack it up, be sure to use jack stands.

Find a container large enough to hold the contents of the tank, you may want to have a backup with in easy reach.

The fuel strainer on the wagon does not have a hose attached to it like the D and SD, it is just a 46mm low prophile bolt in the middle of the bottom of the fuel tank (I got a 1-13/16th" socket from tractor supply for cheap) or you may be able to get it with channel locks or a big adjustable wrench. It is much easier to get at than on the sedans.

Be careful as you unscrew it.

Let the tank drain. Now is a good time to replace those old fuel lines under the car with some good Viton or other synthetic rubber hose.

Clean the tank strainer or replace it. Check that gasket it may be history. A new strainer should only cost about $20.

Reinstall the strainer.

Refill the tank with clean fuel and a good algea killer (you can get that stuff from marinas and heavyduty truck supply houses)

I would unhook the reutrn line and use the hand pump to pump clean fuel into the lines, collecting the old stuff in a coffee can or something.

Change the filters.

Reprime the system and you are off and running.

Keep using the algea killer or use a percentage of biodiesel, or both, and keep an extra filter or two in the car with you.

Hope that helps, lemme know if I need to explain something better.

As for the old fuel...You may be able to pour it through a coffee filter or two, or maybe cheese cloth, just be sure and use that algea killer if you do put it back. I have a 5 gallon container full of algeafied fuel that I am afraid to do anything with, even though I have a centrifuge oil filter that would take out the particles, I just don't want another contamination problem.

Joe

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1987 250D
1984 300TD
1983 300D
2002 Chevy 2500HD Diesel
1995 Dodge 12 valve Cummins Dually
All Biodiesel Powered