Fuel filter placement

[MagikDraggin]

There is an in-line fuel filter just ahead of the fuel pump (on the suction side of the pump), on my '62 Hawk.

I was recently told by a supposed informed person, that this is NOT a good place for a fuel filter, as it can contribute to vapor lock, besides placing undue stress on the pump itself from having to "pull" fuel through it.

Is there any validity to this concern? I have not had any vapor lock problems with this GT, but I am on my 3rd fuel pump in a year and a half.

Karl '62 GT Hawk 4sp

[showbizkid]

StudeRich just posted in another thread that the suction side is actually where you want it, because it's less prone to leak than when it's pressurized.

As for the vapor lock thing, that's hogwash. If the filter's down where there's no heat to speak of, there's no reason for the fuel to vaporize.


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Clark in San Diego
'63 F2/Lark Standard
http://studeblogger.blogspot.com
www.studebakersandiego.com

[Mike]

It's supposed to be a bad idea to put a filter on the suction side of the pump. Any added restriction reduces pressure further below atmospheric. That lowers the boiling point of the fuel inside the filter and the line between the filter and pump.
That's the theory. In fact, I think most people who add a filter there "get away with it". An old tank can put a lot of crud in the system. Although the valves in the pump are supposed to be self cleaning, you may want a filter to protect them. A big filter, mounted away from heat would be best.
I think there's only the potential vapor lock problem with the filter. I don't see how it would "stress the pump".
Mike M.

[BobGlasscock]

Speaking in terms only of liquid properties, pumps, and filters, a filter on the suction side of a pump will reduce the pumps effectiveness if and when it reaches a 'clogging' state. Result with a car -- runs out of gas in carb. Pumps can only push what they can suck. The amount of liquid (gas) flow is the same on either side of a clean filter, whatever the pump can suck. If the filter is dirty, the flow is decreased (on both ends of the filter -- Newton's law of action/reaction) and the fact that the pump cannot get enough fluid may or may not deteriorate the pump mechanics. Depends on if the pump design engineering allows the pump to work with no load with no damage. I don't know how the car engineers engineered gas pumps, but my guess is that no load (with a dirty filter) would damage the pump over time. But, I would imagine that the immediacy of poor performance would lead the owner to check and clean the filter long before that time could arrive.

'50 Champion, 1 family owner

[MagikDraggin]

Thanks to all who responded. Looks like I'll leave the filter where it is, (and yes, it is clean), and not try to 'fix it' if it ain't broke.

Regarding the fuel pump failures I mentioned; after two bad experiences with those purportedly "hi-quality" CARTER pumps, I decided to go back to a lessor-expensive generic pump, which by the way, is still pumping just fine.

Karl '62 GT Hawk 4sp

[showbizkid]

Well now I'm curious as to where the factory instructions for the accessory fuel filter said to place it. If you place it after the pump, you'd need to cut the factory fuel pipe... I wouldn't want to do that.


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Clark in San Diego
'63 F2/Lark Standard
http://studeblogger.blogspot.com
www.studebakersandiego.com

[StudeRich]

All of the "SP" metal fuel filters I have ever seen, are installed right where the fuel filter/pressure return port unit would be on a Jet Thrust or Avanti, midway between the outboard edge of the cyl. head and the Carb.

StudeRich
Studebakers Northwest
Ferndale, WA

[Andy R.]

I recently added one in the spot you described. Out of concerns you mentioned, I mounted it horizontally with the outlet side slightly lower than the inlet. It likely makes no difference. It is easily inspected, easily swapped and most importantly, protects the pump from debris.

With gas prices, I've resorted to the cheapest stations, which may not have the cleanest supply tanks or, conversely, may have sediment stirred by frequent filling. A couple of these little filters (Napa Gold #3002) in the trunk are peace of mind.

I'd have preferred to mount it near the tank outlet, but didn't relish the idea of leaking $$ gas to replace it. That might have qualified me for CASO status?!
*fingers crossed*

Andy
62 GT