<VV> Healthy pumps?

[corvairduval at cox.net]

That's right Ron, the fuel pump provides relatively constant pressure (from
the spring) of fuel to the carbs and the needle/seat shut the flow off when
not needed. The valves in the pump are just one way check valves to keep
the fuel from flowing backwards. The spring is the only item in the pump
that exerts pressure on the output diaphram. The crankshaft only applies
force to suck the fuel into the pump. Take one apart and look at the pieces.

Or read John Moody's article.

I will supply this article to any one who wants to read it. A great
explanation of how the pump works.

Again, The spring is the only item in the pump that exerts pressure on the
output diaphram. The crankshaft only applies force to the diaphram to suck
the fuel into the pump. When the pump is full of fuel and the float holds
the needle and seat closed, the diaphram does NOT move even though the
crankshaft is pushing up every revolution. Therefore no flow, but pressure
is available for when the needle and seat opens.

Whether or not 9 psig is too much for the float to react against to stop
the fuel flow should be evident, i.e. is gasoline flowing into the venturi
at idle? There should not be liquid gasoline flowing at idle in the venturi
area.


If there are other Corvairs in the area, one can easily swap the fuel pump
or carb set temporarily to see if the problem follows the pump or carbs.

Frank DuVal


Original Message:
-----------------
From: Ron ronh at owt.com
Date: Thu, 17 Jul 2008 13:06:42 -0700
To: corvairs at pacifier.com, jkean at sbcglobal.net, virtualvairs at corvair.org,
corvairduval at cox.net
Subject: Re: <VV> Healthy pumps?


The float valves turn the flow on and off.  The fuel pump provides a design 
pressure whether it's on or off.
RonH

----- Original Message ----- 
From: "corvairs" <corvairs at pacifier.com>
To: "Jack Kean" <jkean at sbcglobal.net>
Cc: <virtualvairs at corvair.org>; "Frank DuVal" <corvairduval at cox.net>
Sent: Thursday, July 17, 2008 1:17 PM
Subject: Re: <VV> Healthy pumps?


> Jack - This current hysteria about fuel pump pressure is an internet red
> herring.  Mechanical pumps have put out that kind of pressure all along.
> (or at least, it is within range). Are you having problems that have
> lead you to look at pump pressure?  By the way (to you guys who said
> that the valves don't regulate the flow of fuel under pressure) how then
> does the stock Corvair system "shut itself off" (stop fuel flow) when
> the carb bowls are full or when the secondaries are closed?    Lon
>
>
> www.corvairunderground.com
>
>
> Jack Kean wrote:
>> I inserted a fuel pressure gauge in the fuel line, in place of one of
>> the secondaries in my 140 hp yesterday. It was registering around 8
>> pounds at idle, 9 pounds per square inch off idle. Seems at least double
>> the numbers listed in the shop manual. I am not sure of the source of
>> this mechanical pump, since it was on the car when I purchased it. I
>> will be looking into a fuel pressure regulator, which I will be able to
>> continue to use if I chose to change to an electric fuel pump.
>>
>> jack kean
>>
>>
>
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