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In article ,
says...
says...

Is it possible to put two fuel filters in series on one line?

Yes, it's very common

... I want
to do this because I am afraid there is a lot of debris in my gas tank
and I figured it might allow me to change out the first filter out on
the water?

What you want is two filter in parallel, not series...
prob'ly that's what you meant? Also a common arrangement; in
fact many boats have two primary filters in parallel so as
to be switched underway, and then two secondary filters in
series mounted on the engine itself between the lift pump
and the injector pump.

jps wrote:
A good idea and it'd be best to start with a coarser filter and put a
finer filter in the second unit.

I disagree. Why bother with a filter that's not small
enough? Why set up your system so that if one filter fails,
the other will clog and pull the engine off-line instantly?
Why have your system set up so that you have to change the
second filter as often... or more... than the first?

... They'll do a better job by exposing
more filter surface to trap different sized particles and thereby help
ensure the first filter doesn't get clogged by smaller particles.

That's not the way filters are designed. If you understand
the specs on a filter, it is rated for the same flow & has
the same filtration surface area regardless of the fineness
of the filter element placed in it.

Doug, if the first filter is responsible for both large and small
particles, isn't it going to clog more quickly?

The point is that you're distributing the gunk across a larger surface
area by doing it in series.

For example I use a Racor 45gph filter (which is very much
more flow than my engine will ever use) with 2 micron
elements in in, as a primary. It will seperate water and
trap everything I want to keep out of the engine. Changing
the element is much easier than rebuildin the injector pump.
It is rated at 45gph whether you put in the 30, 20, 10, or 2
micron element.

Obviously the 2 micron element will clog quicker, but that's
what you *want* it to do: keep that gunk out of the engine.
And why put in a 30 then a 2 and have to change them both?

Because it'll take twice as long to clog?

If you really want to set up your system to not have to
change fuel filter elements, then just don't have one at all
and rebuild your injection system annually. Wouldn't that be
easier & cheaper??

You've assumed he's a diesel user, but when someone uses the phrase "gas
tank" I assume it's gas.

We're assuming different kettles of fish.

jps