Fuel filter location

GBowman · #1 (**permalink**) 10-15-2012, 02:34 PM

I have a mechanical fuel pump, is it best to push fuel through the filter or pull through the filter? Does it make a difference?

Thx

Rick Parker · #2 (**permalink**) 10-15-2012, 06:43 PM

Gary I too have mechanical pump since day 1 and have the filter at the rear of the car in front of the tank at what would be 1/2 full level in tank. Fuel is taken out the top of the cell.

Jaydee · #3 (**permalink**) 10-16-2012, 07:49 AM

A mechanical pump is much stronger at sucking, Its pulled down by the cam, not pushed up by a spring. It'll also stop any dirt from wedging under the one way valves. Only problem, is if you have a restricted filter, on a hot day, the fuel will boil at a lower temp, causing vapor lock.
JD

PANAVIA · #4 (**permalink**) 10-22-2012, 05:50 AM

both - there should be a filter from the tank to the pump, and a second smaller inline Pump to carb/EFI.

stallion112 · #5 (**permalink**) 10-22-2012, 10:16 AM

If you install a filter on the inlet side to the pump make sure it is 100 microns. A typical fuel filter is either 10 or 35 microns (intended for placement after the pump on the pressure side) and they are way too restrictive for the inlet side. The restriction can cause a vacuum to form just after the filter, especially on a hot day. You may then find yourself under the car removing the fuel line to purge the air pocket. Been there.

WardL · #6 (**permalink**) 10-23-2012, 01:35 AM

All reputable retail pump dispensers have 10 micron filters on gasoline. A 100 micron filter is just getting the chunks out of the fuel coming from the tank. Why do you think you need two filters for a carburetor system? All the holes in a carb are way bigger than 100 micron. Filters are not really required in carburetor systems. They are more important in fuel injection systems, but that may be debatable. For your peace of mind, put in a 100 micron filter between the tank and the carb. It is so big at 100 micron it will rarely foul up and cause a problem. Has anyone EVER had a problem and after changing just the filter the problems went away? Hello? Anyone?

stallion112 · #7 (**permalink**) 10-24-2012, 12:16 PM

Yes, as I stated previously, the more restrictive filter on the suction side of the pump caused a vacuum to form. Switching to the less restrictive 100 micron filter solved the problem. 100 micron media is sufficient for catching larger chunks such as fuel cell foam or larger sediment from the filling station tanks. The finer 35 micron filter at the carburetor protects the carburetor.

zrayr · #8 (**permalink**) 11-04-2012, 10:51 PM

I used a 10 micron Golan filter for about 9 years on a '66 GT350 with a vintage Paxton. It was before the pump. I put about 50,000 miles on that car over that time period and never had a problem with the filter. Numerous high speed endurance runs were made in the car with sustained speeds over 120 mph.

Am now using the same model of filter on a '65 K code with a set of 48IDA Webers. This time around I put the filter after the pump (purely for cosmetic reasons) Again no problems.

Z,