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Re: [Mgs] Fuel Pump?

To: "Michael MacLean" <rrengineer.mike@att.net>, "Mglist" <mgs@autox.team.net>
Subject: Re: [Mgs] Fuel Pump?
From: "PaulHunt73" <paulhunt73@virginmedia.com>
Date: Mon, 11 Jan 2021 08:29:15 -0000 nVxlto9baa8g9Qbz176VEbWSMtS/LWfSo+9h41uWVFEUubjoTKH1hxstmRdQTB3J1YjLcaBH7JddpBl5Hk5kgaYjCqrnYadOliY=
Delivered-to: mharc@autox.team.net
Delivered-to: mgs@autox.team.net
References: <579080298.451759.1610314370698.ref@mail.yahoo.com> <579080298.451759.1610314370698@mail.yahoo.com>
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Could be several things, but unless it was pumping fuel onto the ground =
it's more likely to be associated with the pump itself.

An air leak on the suction side is unlikely to seal itself again, for =
more than a couple of minutes anyway.  A blockage does allow the pump to =
pump more rapidly than when pumping fuel, but not as rapidly as when =
it's not pumping fuel for other reasons e.g. valve stuck open or pumping =
air.

As the idle dropped, and only cut out a minute or so later, the =
implication is that the fuel supply was greatly reduced, not cut off =
altogether at the outset.

It could be the one-way valve in the pump inlet allowing fuel to be =
pushed back towards the tank instead of the carbs, possibly dirt =
although there should be filters there - in an original SU anyway.

A delivery check is the thing to do, remove a pipe from a carb, direct =
it into a container and turn on the ignition.  It should deliver a =
minimum of one Imperial pint per minute, and in practice double that, in =
a continuous stream of pulses with minimal bubbling.  Bubbling =
especially variable implies a suction side air leak, without that =
hesitation with the pump speeding up implies the valve is not sealing.

PaulH.


  ----- Original Message -----=20
  ...
  The fuel pump on my 69 GT started pumping furiously like I was running =
out of gas while stopped halfway through the line.  The car was still =
running.  I got up to the first window to pay and the idle dropped to =
less than 500 rpm.  In a minute or so later the engine just quit.  There =
is over a half tank of gas in the car.  I tried starting it several =
times, but it would just fire and die.  After several attempts the car =
started again, all the while the fuel pump was going like mad.  After =
getting out of the line the fuel pump slowed down like normal and you =
did not hear it after what I assume was a full float bowl.  No issues =
going home the 4 or 5 miles.  Does that sound like my fuel pump is going =
out or the tank pickup is clogged?
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<DIV><FONT size=3D2>Could be several things, but unless it was pumping =
fuel onto=20
the ground it's more likely to be associated with the pump =
itself.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>An air leak on the suction side is unlikely to seal =
itself=20
again, for more than a couple of minutes anyway.&nbsp; A blockage does =
allow the=20
pump to pump more rapidly than when pumping fuel,&nbsp;but not as =
rapidly as=20
when it's not pumping&nbsp;fuel for other reasons&nbsp;e.g. valve stuck =
open or=20
pumping air.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>As the idle dropped, and only cut out a minute or so =
later,=20
the implication is that the fuel supply was greatly reduced, not cut off =

altogether at the outset.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>It could be the one-way valve in the pump inlet =
allowing fuel=20
to be pushed back towards the tank instead of the carbs, possibly dirt =
although=20
there should be filters there - in an original SU anyway.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>A delivery check is the thing to do, remove a pipe =
from a=20
carb, direct it into a container and turn on the ignition.&nbsp; It =
should=20
deliver a minimum of one Imperial pint per minute, and in practice =
double that,=20
in a continuous stream of pulses with minimal bubbling.&nbsp; Bubbling=20
especially variable implies a suction side air leak, without that =
hesitation=20
with the pump speeding up implies the valve is not sealing.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>PaulH.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: =
black"><B>...</B></DIV>
  <DIV=20
  style=3D"FONT-FAMILY: times new roman, new york, times, serif; =
FONT-SIZE: 16px"=20
  class=3Dyahoo-style-wrap>
  <DIV dir=3Dltr data-setdir=3D"false">The fuel pump on my 69 GT started =
pumping=20
  furiously like I was running out of gas while stopped halfway through =
the=20
  line.&nbsp; The car was still running.&nbsp; I got up to the first =
window to=20
  pay and the idle dropped to less than 500 rpm.&nbsp; In a minute or so =
later=20
  the engine just quit.&nbsp; There is over a half tank of gas in the =
car.&nbsp;=20
  I tried starting it several times, but it would just fire and =
die.&nbsp; After=20
  several attempts the car started again, all the while the fuel pump =
was going=20
  like mad.&nbsp; After getting out of the line the fuel pump slowed =
down like=20
  normal and you did not hear it after what I assume was a full float=20
  bowl.&nbsp; No issues going home the 4 or 5 miles.&nbsp; Does that =
sound like=20
  my fuel pump is going out or the tank pickup is=20
clogged?</DIV></DIV></BLOCKQUOTE></BODY></HTML>

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