I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
I had that setup in my series 3 for a while. used a Carter pump with a
toggle on-off-of switch, a three way valve on the suction side and a T on
the output side.
Switching pump / filters was just a matter of flipping the switch and valve.
since the Carter pump failed and later on the SU pump failed and I decided
not to rebuild/replace it, I am now running a single Holley Red pump. there
shoudl be reliable so I haven’t installed another one but will get a spare
just in case… It’s just a few minutes to swap so I don’t thinkg I’ll
complicate everything again with a dual set up. If I do, I will probably
use non return valves on the suction side instead of a 3 way valve this way,
it’s just a matter of flipping the switch.
Pascal
72 2+2----- Original Message -----
From: don.beken@uncp.edu
To: e-type@jag-lovers.org
Sent: Thursday, April 03, 2003 10:29 AM
Subject: [E-Type] Fuel pump.
I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In reply to a message from don.beken@uncp.edu sent Thu 3 Apr 2003:
Why on earth go to all that trouble? If you don't trust your
pump, why not put in a single good pump and be done with it?
There are dozens of good, reliable, modern, inexpensive pumps out
there. When’s the last time you had a fuel pump fail in a modern
car?–
The original message included these comments:
I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.
–
Ray Livingston
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In reply to a message from don.beken@uncp.edu sent Thu 3 Apr 2003:
I have done this on four cars using the small solid state fuel
pumps,however I have hooked it up in series. I have used it twice
now and gas flows fine with either pump working. I mounted the pump
on the fire wall on the spare bracket next to the windshield washer.–
The original message included these comments:
I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.
–
Dick North
Prescott, AZ, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Don,
Nope haven’t done it but I’d think you’d want to put it in series.
Would likely work in parallel but the dead pump would have to be working
well enough that the check valve would stop your new pump from pumping
fuel bacward through it.
pauls 67ots
I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.
<<<<<<<<<<
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomoFrom: don.beken@uncp.edu
Subject: [E-Type] Fuel pump.
In reply to a message from paul spurlock sent Fri 4 Apr 2003:
I should probably mind my own business, but I'm still baffled
by the logic of installing redundant pumps, rather than just one
reliable one. This is particularly baffling, as I have never had
a fuel pump fail suddenly in over 30 years of driving all kinds of
cars.
One of the many useful things I learned in engineering school
is that in trying to make a system more reliable, it’s really easy
to actually do exactly the opposite. By installing two pumps,
regardless of how you plumb them in, you’re almost certainly
adding new potential failure modes. Adding complexity, in
general, adds new, more complex failure modes. As an example,
whether you put the two pumps in series or parallel, you are still
almost certainly dependant on the check valves in both pumps to
function, at least to some extent. A failed check valve in
the ‘‘backup’’ pump can render the ‘‘primary’’ pump useless, and vice-
versa. In addition, by having the backup pump exposed to gasoline,
but non-operational, I would think you actually increase the odds
of some ‘‘wet’’ mechanical part getting gunked up and failing, or
being non-operational when/if you do ever try to put it into
service.
Just my two cents worth…–
Ray Livingston
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In a message dated 4/3/03 8:55:11 PM Pacific Standard Time,
rayl@atc.creative.com writes:
<< I would think you actually increase the odds >>
I agree with Ray.
Normally, with a twin engine airplane (which will fly on a single engine,)
you have twice the chance of an engine failure, but only half the chance of
losing your LAST engine. Instead, you have twice the chance of failure-period!
Just my thoughts!
Mike Moore
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
To all
in my Chevy Pickup I am using a small (German made, Pierburg) pump
in series with the motor driven standard pump since more then ten
years without any problems. I planned to use it as a backup but never
had the chance, so it only comes into action in spring when I first
start the car after the winter pause.
Peter Herzog
888220
paul spurlock schrieb:
Don,
Nope haven’t done it but I’d think you’d want to put it in series.
Would likely work in parallel but the dead pump would have to be working
well enough that the check valve would stop your new pump from pumping
fuel bacward through it.
pauls 67otsFrom: don.beken@uncp.edu
Subject: [E-Type] Fuel pump.I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.
<<<<<<<<<<Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Ray,
I totally agree with that logic. Adding plumbing alone increases the
chances for failure.
I have had a pump fail tho but given that was last year and the car is
36 years old with 120k miles on it, it hardly justifies such reduncancy
does it 
pauls 67ots
I should probably mind my own business, but I'm still baffled
by the logic of installing redundant pumps, rather than just one
reliable one. This is particularly baffling, as I have never had
a fuel pump fail suddenly in over 30 years of driving all kinds of
cars.
One of the many useful things I learned in engineering school
is that in trying to make a system more reliable, it’s really easy
to actually do exactly the opposite. By installing two pumps,
regardless of how you plumb them in, you’re almost certainly
adding new potential failure modes. Adding complexity, in
general, adds new, more complex failure modes. As an example,
whether you put the two pumps in series or parallel, you are still
almost certainly dependant on the check valves in both pumps to
function, at least to some extent. A failed check valve in
the ‘‘backup’’ pump can render the ‘‘primary’’ pump useless, and vice-
versa. In addition, by having the backup pump exposed to gasoline,
but non-operational, I would think you actually increase the odds
of some ‘‘wet’’ mechanical part getting gunked up and failing, or
being non-operational when/if you do ever try to put it into
service.
Just my two cents worth…
Ray Livingston
Santa Cruz, CA, United States
<<<<<<<<<<
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomoFrom: Ray Livingston rayl@atc.creative.com
Subject: Re: [E-Type] Fuel pump.
Hello Ray,
Ah, the whole point of redundancy is the statistical
chance of both systems failing at the same time.
While it is twice as much complex and has twice
the chance of a failure (thus yielding no apparent net
advantage) the chance of both failing at the same time
are much smaller.
If you have a system with an MTBF of 10,000 hr. and you
make it 100% redundant, the combined MTBF goes up
to 100,000 hr. There are some conditions. Both systems
have to be monitored for health and you have to repair any
failure quickly (low MTTR) to realize the increase in MTBF.
Microwave transmission systems are always 100% redundant
for that reason and the concept works pretty well…
Dick Vandermeyden
San Carlos, California
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In a message dated 4/4/03 8:19:21 AM Pacific Standard Time, Vand116@AOL.COM
writes:
<< chance of both systems failing at the same time. >>
I thought the premise was either that pump failing would cause a problem. For
instance, the brakes on the S1 (like mine) have two master cylinders. Due to
the treadle (whiffletree) design, losing either master cylinder will cause
total braking failure (Don’t ask me how I know!). So in that case, they have
far less reliability with two master cylinders.
Mike MOore
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Careful Dick this is a dangerous though process that could ultimately
lead one to think that owning 2 E-Types is actually a sensible and
practical way to insure non-stop availability of an English motoring
system.
Eric___________________________________________________________
Hello Ray,
Ah, the whole point of redundancy is the statistical
chance of both systems failing at the same time.
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In a message dated 4/4/03 8:35:22 AM Pacific Standard Time,
emalossi@austin.rr.com writes:
<< Careful Dick this is a dangerous though process >>
It just dawned on me that my XJ6 S1 had dual fuel pumps AND dual tanks!
Mike Moore
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In reply to a message from Vand116@aol.com sent Fri 4 Apr 2003:
Dick,
I have to strenuously disagree with you here. In your example,
the chances of both pumps failing at the same time would be
100,000 hours. But, we’re not talking about simultaneous failures
here. It only takes a single failure in the right place for
both pumps to be rendered useless. So, the MTBF in this case
does not go up, it goes down, and sharply at that. If we were
talking about truly independant redundant systems, I would agree
with you that the MTBF could be increased. However, simply
hanging another pump in the boot constitutes anything but 100%
redundancy. As a failure in one pump can easily render both
useless, you now have at least twice the opportunity for failure,
so your MTBF will go sharply down. And, as I also pointed out,
simply having a pump plumbed in but non-operational may induce
additional failure modes which will reduce the MTBF of
the ‘‘backup’’ pump well below what it would be were it actually in-
service. Also, you’re adding more plumbing and wiring, which
further reduces MTBF.–
Ray Livingston
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In reply to a message from MMoore8425@AOL.COM sent Fri 4 Apr 2003:
Mike,
That was done for packaging reasons, wasn’t it?–
The original message included these comments:
It just dawned on me that my XJ6 S1 had dual fuel pumps AND dual tanks!
Mike Moore
–
Ray Livingston
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In general, built in redundancy is good if failure is catastrophic. E-type
fuel pump failure is generally only inconvenient.
Why not just carry a spare el-cheapo electric pump, with pre-attached hose
barbs and a couple of hoes clamps in the boot as a spare. If the main pump
goes out, just plumb in the emergency spare and go on your way. That is one
of the reasons why I have used the regular black fuel line from my gas tank
to the pump. I can splice in a second pump and be back on the road in ten
minutes or so. Now I just need to buy the el-cheapo pump I keep promising
myself. 
Regards, John Walker
69 2+2
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
As I said before in the thread about what spare parts to bring on a trip, if
you have a “wobbly” fuel pump, either repair it or replace it. If you had
an old, cracked fuel line, would you run another fuel line next to it, with
changeover valves, in case the first one sprung a leak? I hope not.
By the way, the Series III comes with a redundant fuel pump. It has two
separate independant pumps, plumbed in parallel, in order to achieve the
flow necessary at high revs and loads. The upshot is that if one of them
dies, the other will still provide enough fuel to get you home.
Mike Eck
Smiths clock electronic upgrade
Jag-Lovers Picnic at http://www.jag-lovers.org/events/event_view.php3?id=280
I would like to install a fuel pump in parallel with the original
pump in the car. That is, if the wobbly fuel pump goes, then I can
switch to the back up. Has anyone done such a thing? What pump
was used etc.
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
In a message dated 4/4/03 9:25:59 AM Pacific Standard Time,
rayl@atc.creative.com writes:
<< That was done for packaging reasons, wasn’t it? >>
To the contrary, it was done to decrease the reliability!
Actually, they were a royal pain. I was constantly plagued with fuel pump and
hose leak problems. You’re right -the XJ6 had two small tanks instead of one
large one.
Best, Mike
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Walker, John JR SITI-ITDFP writes:
Why not just carry a spare el-cheapo electric pump, with pre-attached hose
barbs and a couple of hoes clamps in the boot as a spare. If the main pump
goes out, just plumb in the emergency spare and go on your way.
Actually, the original style Lucas pumps can often be found on sale for
under $100. I think mine was $89 at Moss Motors.
Buy a spare and carry the proper size wrench and all you have to do is swap
the banjo fittings from one pump to another and plug in the wires. A 10-15
minute job at worst case.
(But I like the idea of TWO e-types to assure 100% up-time, Eric!)
George Cohn
'70 OTS
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Hey Ray,
Do you realy understand the concept of installing redundant systems for
improving the reliability ?
Indeed it requires carefull analyses of failure modes, for example, a
stikking fuel pump could have side effects, like leaking, creating a
pressure drop. So in this case we want a constant presuure, connect them
parallel, let them working constantly (a not used fuel pump tends to stop
working). In order to prevent pressure drops when one stops, add a check
valve. Indeed the reliability of a check valve should be compared to a
sigle fuel pump. If a broken check valve causes leaks or the average
lifetime of a check valve is less the a fuelpump, then it should be better
to stick at one fuelpump.
conclusion, it is to simple to talk in general about failure posibilities,
it requires carefgull analyses.
Wilko Pels
etype 71 ots under construction
At 18:38 4-4-2003, you wrote:
In reply to a message from Vand116@aol.com sent Fri 4 Apr 2003:
Dick,
I have to strenuously disagree with you here. In your example,
the chances of both pumps failing at the same time would be
100,000 hours. But, we’re not talking about simultaneous failures
here. It only takes a single failure in the right place for
both pumps to be rendered useless. So, the MTBF in this case
does not go up, it goes down, and sharply at that. If we were
talking about truly independant redundant systems, I would agree
with you that the MTBF could be increased. However, simply
hanging another pump in the boot constitutes anything but 100%
redundancy. As a failure in one pump can easily render both
useless, you now have at least twice the opportunity for failure,
so your MTBF will go sharply down. And, as I also pointed out,
simply having a pump plumbed in but non-operational may induce
additional failure modes which will reduce the MTBF of
the ‘‘backup’’ pump well below what it would be were it actually in-
service. Also, you’re adding more plumbing and wiring, which
further reduces MTBF.–
Ray Livingston
Santa Cruz, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo
Wilko Pels
Amsterdam; The Netherlands
Alfa 156 2.0 TS 98: daily use
E-type 70 OTS just passed the dutch government car inspection
Search the archives & forums - http://search.jag-lovers.org/
Subscription changes - http://www.jag-lovers.com/cgi-bin/majordomo