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Eric64 12-25-2010 02:41 PM

Discharge fuel filter?
Can I mount a traditional (usual suction) fuel filter on the discharge side of the mechanical fuel pump on a SBC, to filter the gas before it enters the carb? I didn't know if they would break down and cause more problems or what type of filter do I need, right now I have a 3/8" hose barb on the pump leading into a 3/8 line going to the regulator. It's a low pressure Edelbrock pump. Thank you

DanielC 12-25-2010 03:45 PM

General rule of thumb is you want as few connections on the pressure side of the fuel pump as is possible.

bondo 12-25-2010 04:29 PM

Ayuh,... You want the filter Before the pump, to Save the pump for any Crap...
The check-valves in the pump are as touchy as any carb about Crud...

kc8oye 12-25-2010 10:54 PM

i've always understood it that you never want filters on the suction side of the fuel pump, the suction can collapse the filter media and cause starvation problems. always filter on the pressure side.

I had a filter on the suction side by the tank and it was causing me all kinds of headaches that went away after I got rid of it, and moved to a filter just infront of my regulator.

This pic here isn't the greatest pic for this, but you can see my regulator and filter setup, all mounted by the carb on the passenger side.

302 Z28 12-26-2010 09:16 AM

A filter on the suction side of the pump is always a good idea. You must however use the correct filter. Not a pleated paper filter that can collapse. Use a sintered bronze filter or a filter with a fine metal screen that can be taken apart and cleaned if needed.


bondo 12-26-2010 10:59 AM

Ayuh,... This is what We use on boats, 'n it's ALWAYS before the fuelpump...

kc8oye 12-27-2010 10:37 AM

if it was such a great idea, why is it that they aren't used in production? the filter is always on the pressure side. Even back in the carb'd days, the filters were AFTER the pump.

DanielC 12-27-2010 10:55 AM

You have to realize that everything that is a on a car goes through a cost analysis.
If you can save even a penny in the cost of a part, used in making a car, you multiply that penny by the number of cars made using that part, and the auto company saves thousands of dollars.

Fuel filters are after the pump on modern cars for one reason. The fuel pump is in the gas tank.

matts37chev 12-27-2010 11:03 AM

and those in-tank fuel pumps have a screen/filter mounted on the pump itself as part of the inlet to the pump (before)

airboat 12-27-2010 11:10 AM

Yeah the in-tanks have a pretty effective sock. Most after-market fuel pump manufacturers will recommend a filter on the inlet side of the pump. The one Bondo posted a pic. of is inexpensive, convenient and large enough to do a great job. really need it especially with a vane type pump.

kc8oye 12-28-2010 12:03 AM

yeah.. that's why my 1972 Monte carlo had a fuel sock in the tank, and a filter _AFTER_ the pump. (from the factory)

if it was such a great idea to put it before, don't you think they would have?

it's much much harder to 'suck' then it is to 'blow' think about how little airflow you feel in front of the radiator fan, vs behind it..

matt167 12-28-2010 02:32 PM

from the factory, some didn't even have filters, and just had the sock in the tank..most vane and rotor electric fuel pumps require filters before the pump... factory didn't do it because the sock was there

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