Fuel pump

[Thomas Wright]

Jennifer Rose wrote:

> Hi All
>
>         Had my fuel pump give out on me today. Due to the heat 100+
> deg.
> Going to fab heat shield to try to band aid problem. The setup in the
> pu is
> a low press pump, small storage tank, high press pump - high press
> pump is
> the one quitting . Anyone have suggestions or ideas? This the third
> time in
> 2yrs.
>
> Vance

 I installed a fuel injection system on my previously cabuerated car
about a year ago.  I started having some driveability problems a few
months ago and finally figured out it was my fuel pumps.  I think it is
all three of them!  The car has two gas tanks with in-tank (low
pressure) fuel pumps feeding the main fuel injection (high pressure)
pump.  (Only one low pressure pump feeds the high pressure pump at a
time.  Only one tank is in use at a time.)
One of the in-tank fuel pumps failed completely, and now, after running
off just one tank, the others are going bad (one or both, I think both.)

I have always heard that keeping the in-tank, low-pressure pumps to feed
the high-pressure fuel injection pump was a good idea, but now I am
beginning to wonder.
Since fuel in the fuel injection systems circulates, there is a much
higher flow-rate than with carburetor systems that must only fuel what
the motor needs at the moment.
Could it be that the pumps that are designed for carburetors can't keep
up, and thus they burn out?  Then the lack of decent flow can in turn
burn out the fuel injection pump?  Maybe the fuel injection pump is
fighting even a good low-pressure pump and thus burns out?
I have figured out that MY (maybe not yours) low pressure pumps will
only pump to their capacity and no more (even if you try to "suck" more
out of them.)  I figure this because if you unplug the power from them
and remove the fuel hose, not a drop will come out, even with a full
tank.  I think this would definitely put a strain on the high pressure
pump if the low pressure pump could not keep up with its capacity.

Tom Wright