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Old 05-02-2006, 09:25 PM
72NOVA454
 
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Fuel Filter Location

question

does it matter which side my fuel filter is located with respect to my mechanical fuel pump? should it go before or after the pump or doesnt it matter? I have a engine mounted, cam actuated fuel pump on my BB 454 Chevy feeding a dual inlet Holley 750. I've had the filter after the pump on previous occasions and it appears full of fuel and worked well. Now it's on the inlet side of the fuel pump and I may be having fuel starvation problems at wide open throttle and the fuel filter "glass bowl" does not appear to be full of fuel, there is air in there occupying about 50% of the volume. Is that ok? I"ve got a new carb on there so I'm not sure if it's the carb of the fuel filter location causing the fuel starvation problem. Fuel bowl levels were checked and appears to be ok.

thanks.

Lee

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Old 05-02-2006, 10:44 PM
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turbo lag......yeeeeehaaaaaaw
 
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all filter I have seen are after the pump except on electic pump set ups.
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Old 05-02-2006, 11:15 PM
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Put the filter after the pump, mechanicle pumps are much better at pushing than pulling.
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Old 05-03-2006, 07:21 AM
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for as little as they cost....2 is better....

one before the pump to keep tank crap from going thru the rubber pump diaphram, damaging it, and to keep the pump from grinding the crap so small it can get past the second filter after the pump

a horizontal in and out mounted clear filter that is totally full of gas with the motor running is a filthy plugged filter, one that is 1/2 full of gas is a clean filter

don't use a clear plastic filter after the pump, I do use a clear Fram filter before the pump, easy to tell if it's filthy, "no gas" in the filter is a plugged tank pick up or "outta gas"

a fuel pump is a "suction" diaphram pump with a one way check valve on the output side that builds the pressure, not the same as a oil (push) pump or other
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Old 05-03-2006, 08:00 PM
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Quote:
Originally Posted by red65mustang
for as little as they cost....2 is better....

one before the pump to keep tank crap from going thru the rubber pump diaphram, damaging it, and to keep the pump from grinding the crap so small it can get past the second filter after the pump

a horizontal in and out mounted clear filter that is totally full of gas with the motor running is a filthy plugged filter, one that is 1/2 full of gas is a clean filter

don't use a clear plastic filter after the pump, I do use a clear Fram filter before the pump, easy to tell if it's filthy, "no gas" in the filter is a plugged tank pick up or "outta gas"

a fuel pump is a "suction" diaphram pump with a one way check valve on the output side that builds the pressure, not the same as a oil (push) pump or other
well with the filter on the pump inlet, the car runs like crap at wide open throttle. when I removed the filter (no filter) the car tears up the street and runs good. I don't feel comfortable putting it before the pump if that is what is going to happen. when the filter was after the pump it also ran well but I had to move it due to engine rebuilding and modifications.
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Old 05-04-2006, 05:17 AM
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leejoy,

in your case, "something(s)" is/(are) "borderline", the filter before the pump is telling you there is a problem....it's another reason I do like to have a filter before the pump

possible weak fuel pump WOT and/or no gas tank air vent and/or tiny air leak between the tank and the pump and/or restricted tank pick up?

what your seeing is the pump is not able to pull enough gas on each stroke because it will pull a vacuum on the air in the filter first....that should not happen

analogy? suck soda thru a straw, put a hole in the straw above the liquid...good luck.....block the bottem of the straw.....good luck....suck just a tiny bit....don't work

I'll go out on a limb and say virtually every stock carbed motor came with a filter before the pump....from a econo to a hemi
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Old 05-04-2006, 08:58 AM
Technical Support Barry Grant
 
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Filter locatation

You really should have a filter both before and after your fuel pump. Running one before the pump will increase the life of the pump, while after the pump will help prevent debris from getting into the carburetor.

You need to make sure the filters you use are of a high enough flow rating so that they do not restrict your fuel flow. If your setup isn't working properly with a filter before your pump than either the filter is too restrictive, dirty, or the pump is getting weak.
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Old 05-04-2006, 09:50 AM
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Tech, and others

just for info

the crystal clear $5 Fram filter I meantioned is often not displayed with the rest,
Advance Auto keeps them behing the counter.....so ask
it measures approx 2" dia x 2" tall, 5/16 or 3/8" connects available
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