I was wondering, since the primary fuel filter at the bottom of the pickup tube on my 1800ES isn't in the part of the system that is under high pressure, what is the reason that it's located inside the tank where it's difficult to service. Why wasn't some sort of in-line particle filter used between the tank and the fuel pump? I suppose the stock setup allows the tank to still run if it has a ton of particles in the bottom, but an inline filter would be easier to clean and service. It looks like the previous owner of my car was running it with no primary filter at all (the tank was very clean.) Can anyone enlighten me on this one?

Hello Fran,

For the 1st 2 years of D-jet fuel injection, 1970 and 1971, Volvo used an external low pressure fuel filter inline between the fuel tank and the fuel pump and that was the ONLY fuel filter for the whole system that was very easy to change.

Starting in 1972, Volvo put a low pressure filter into the tank and added a high pressure fuel filter AFTER the fuel pump.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

You SHOLD NOT put a filter in front of a high pressure fuel pump because it will die from cavitation, only a sieve should be used like the little sock that Volvo used on the end of the 1/2" pipe as seen in 140 B20E cars. If a piece crap gets through the sieve and jams the pump, the roll pin will break as intended and can be easily fixed.

Ideally, a low pressure pump of correct output pushing through a filter to feed the high pressure pump is the way to go like Volvo did in later 240's.