I don't run a separate on-board filter, but like everyone else I filter at least twice when pumping from my fuel caddy.

I have been relying on the Air Trap filer as the on-board filter.

I have been using MAP Air Traps with the internal pleated paper filter and I have seen them start to plug-up, resulting in increased pump voltages and even multiple flame-outs. Back-flushing has helped temporarily, but I have gone through at least 3 MAP Air Traps over the last few years in probably 200 flights on 2 models. I add Biobor to every batch of kerosene I buy to kill off any algae.

After the last Air Trap replacement I emptied out my fuel caddy and found a bunch of sludge in the bottom, probably a 5 year accumulation from the pump kerosene I run. This was probably the major source of the gunk clogging the Air Trap as the caddy clunk filter was sitting right in the sludge. Don't forget to change out the caddy filters on a regular basis. An annual fuel caddy cleaning is a good idea too.

An additional filter downstream of the pump would not have helped.


Paul