X2 SEV,
I think there maybe a mix up between the primary filter & the strainer.
The strainer is inside the tank. It will be full of gunk. you need to get at it from under the car. & then drain as much of the gunk/WVO/water as you can.
The primary filter is just before the lift pump. It sounds like that is the one that you found blocked.
Your secondary is probably blocked as well or it will be very soon.

If it was black gunk, best get some anti microbial stuff. There are plenty of recommendations as to the best one.

Your WVO has fed the little critters & they have bred like mad. Its like Viagra for bugs. Your fuel tank has been one giant orgy for them!! Time to return some morality to your tank!!!

Sorry I couldnt resist that.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving