Fuel filter before or after mechanical pump? - Impala Tech
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  • 1 Post By jayoldschool
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post #1 of 3 (permalink) Old 05-03-2020, 03:15 PM Thread Starter
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Location: Washington
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Fuel filter before or after mechanical pump?

I currently have a K&N 1300 filter before my fuel pump but I suspect it might be restricting suction, even more so if it starts getting dirtier. I don't have anything in between the pump and carb.

I know the stock filter originally connected inside the carb connection. So is a filter before the pump really necessary? Isn't there a mesh filter of some kind on the fuel sending unit anyway? Where does everyone place their filters?

1967 Chevrolet Impala 4 door "post" sedan
327 5.4L V8 - 3-speed TH350
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post #2 of 3 (permalink) Old 05-03-2020, 04:35 PM
Join Date: Jan 2006
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You need a 100 micron filter (basically a strainer) before the pump. The factory uses a fabric sock on the end of the inlet tube. After the pump but before the carb you need a ten micron filter (which shouldn't be made of paper with gasohol as fuel). Alternatives to paper are fiberglass mat and stainless steel wool which can be back flushed under high pressure to be cleaned and reused again.

Never use the small plastic 5/16" hose barb clear fuel filters for anything but a lawn mower. They do not have the capacity to feed a high horse engine and quickly clog.

Big Dave
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post #3 of 3 (permalink) Old 05-03-2020, 07:50 PM
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Take the filter off. Put a filter between pump and carb.
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