Parallelling fuel pumps
 

Glenn,

That is pretty much what I was figuring on other than the
check valves. Not sure I want a center off switch though.
I would prefer that one or the other be on at all times. I'm
also considering putting an hours-meter on each so that I
can balance the use.

Doug
s/v Callista

"Glenn Ashmore" wrote in message
news:7wzec.16$uF3.13@lakeread04...
Doug,

The way the Walbro is built, the flow may or may not be blocked
depending on the position that the wobble plate is in. Bottom line if
you want fully automatic change over for backup, plumb them in parallel
with a check valve on the output of each. Then you can wire them to a
SPDT center off switch to shift from one to the other.

Doug Dotson wrote:
Is there no failure mode that would prevent flow through?

Doug
s/v Callista

"Kelton Joyner" wrote in message
.. .

Unless you have isolation valves to allow servicing of a parallel pump,
series works just as well for backup.
fuel wil flow through the unpowered pump.
Kelton
W4IND
s/v Isle Escape

Larry W4CSC wrote:

(Steven Shelikoff) wrote in
:



That begs the question why are you going to put two pumps in parallel
if
you only want to run one at a time?

Steve



Backup?

Larry W4CSC




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Parallelling fuel pumps
 

I seem to recall from the WALBRO docs that the pump is not
field servicable. Specifically, it states that the internal filters
cannot be changed.

Doug
s/v Callista

"Kelton Joyner" wrote in message
.. .
Unless you have isolation valves to allow servicing of a parallel pump,
series works just as well for backup.
fuel wil flow through the unpowered pump.
Kelton
W4IND
s/v Isle Escape

Larry W4CSC wrote:
(Steven Shelikoff) wrote in
:


That begs the question why are you going to put two pumps in parallel if
you only want to run one at a time?

Steve



Backup?

Larry W4CSC

Parallelling fuel pumps
 

I seem to recall from the WALBRO docs that the pump is not
field servicable. Specifically, it states that the internal filters
cannot be changed.

Doug
s/v Callista

"Kelton Joyner" wrote in message
.. .
Unless you have isolation valves to allow servicing of a parallel pump,
series works just as well for backup.
fuel wil flow through the unpowered pump.
Kelton
W4IND
s/v Isle Escape

Larry W4CSC wrote:
(Steven Shelikoff) wrote in
:


That begs the question why are you going to put two pumps in parallel if
you only want to run one at a time?

Steve



Backup?

Larry W4CSC

Parallelling fuel pumps --- better to use a 'day tank'
 

Instead of parelleling electrical lift pumps, better to install a 'day
tank' that is constantly supplied by freshly filtered fuel oil but with
a lock-out cock (to an inverted dip tube in the day tank) so that the
day tank always keeps a full load of fuel. Then if you have electrical
failure or filter blockage you will be able to use the 3 or 4 gallons
in the day tank to keep moving and make repairs, etc. If worse
becomes worse, you can always siphon fuel from the main tank(s) and
manually load a gravity feed 'day tank'.

FWIW ... A Walbro IMHO is NOT a constant duty delivery pump. A better
solution for that application is simply an automotive 12v impulse fuel
pump. The Walbro is an intermittent transfer or recirculation pump;
but, can be so piped that if the engine mounted diaphragm lift pump AND
the inline priming pump BOTH fail then the recirculation pump can be
used to either pressurize the system or deliver to the 'day tank'.

Parallelling fuel pumps --- better to use a 'day tank'
 

Instead of parelleling electrical lift pumps, better to install a 'day
tank' that is constantly supplied by freshly filtered fuel oil but with
a lock-out cock (to an inverted dip tube in the day tank) so that the
day tank always keeps a full load of fuel. Then if you have electrical
failure or filter blockage you will be able to use the 3 or 4 gallons
in the day tank to keep moving and make repairs, etc. If worse
becomes worse, you can always siphon fuel from the main tank(s) and
manually load a gravity feed 'day tank'.

FWIW ... A Walbro IMHO is NOT a constant duty delivery pump. A better
solution for that application is simply an automotive 12v impulse fuel
pump. The Walbro is an intermittent transfer or recirculation pump;
but, can be so piped that if the engine mounted diaphragm lift pump AND
the inline priming pump BOTH fail then the recirculation pump can be
used to either pressurize the system or deliver to the 'day tank'.

Parallelling fuel pumps --- better to use a 'day tank'
 

Interesting. Can you point me to some supporting docs that
indicates the WALBRO is not suitable as a primary pump.
This is counter to all I have heard from numerous sources
including reputable marine service outfits. Actually, the
WALBRO docs that come with the pump includes only
instructions for installing it as a list pump.

More below.

Doug
s/v Callista

"Rich Hampel" wrote in message
...
Instead of parelleling electrical lift pumps, better to install a 'day
tank' that is constantly supplied by freshly filtered fuel oil but with
a lock-out cock (to an inverted dip tube in the day tank) so that the
day tank always keeps a full load of fuel. Then if you have electrical
failure or filter blockage you will be able to use the 3 or 4 gallons
in the day tank to keep moving and make repairs, etc. If worse
becomes worse, you can always siphon fuel from the main tank(s) and
manually load a gravity feed 'day tank'.

Not practical in my case.

FWIW ... A Walbro IMHO is NOT a constant duty delivery pump.

Not my understanding. This pump seems to have been used for many
years as a primary fuel pump and seems to have a very reputation.

A better
solution for that application is simply an automotive 12v impulse fuel
pump. The Walbro is an intermittent transfer or recirculation pump;
but, can be so piped that if the engine mounted diaphragm lift pump AND
the inline priming pump BOTH fail then the recirculation pump can be
used to either pressurize the system or deliver to the 'day tank'.

That is sort of what I have now. Engine mounted mechanical lift
pump with the WALBRO ahead of it. WALBRO can be used
as a backup in the case of a failure although some plumbing
has to be moved to bypass a failed mechanical pump.

Parallelling fuel pumps --- better to use a 'day tank'
 

Interesting. Can you point me to some supporting docs that
indicates the WALBRO is not suitable as a primary pump.
This is counter to all I have heard from numerous sources
including reputable marine service outfits. Actually, the
WALBRO docs that come with the pump includes only
instructions for installing it as a list pump.

More below.

Doug
s/v Callista

"Rich Hampel" wrote in message
...
Instead of parelleling electrical lift pumps, better to install a 'day
tank' that is constantly supplied by freshly filtered fuel oil but with
a lock-out cock (to an inverted dip tube in the day tank) so that the
day tank always keeps a full load of fuel. Then if you have electrical
failure or filter blockage you will be able to use the 3 or 4 gallons
in the day tank to keep moving and make repairs, etc. If worse
becomes worse, you can always siphon fuel from the main tank(s) and
manually load a gravity feed 'day tank'.

Not practical in my case.

FWIW ... A Walbro IMHO is NOT a constant duty delivery pump.

Not my understanding. This pump seems to have been used for many
years as a primary fuel pump and seems to have a very reputation.

A better
solution for that application is simply an automotive 12v impulse fuel
pump. The Walbro is an intermittent transfer or recirculation pump;
but, can be so piped that if the engine mounted diaphragm lift pump AND
the inline priming pump BOTH fail then the recirculation pump can be
used to either pressurize the system or deliver to the 'day tank'.

That is sort of what I have now. Engine mounted mechanical lift
pump with the WALBRO ahead of it. WALBRO can be used
as a backup in the case of a failure although some plumbing
has to be moved to bypass a failed mechanical pump.

Parallelling fuel pumps --- better to use a 'day tank'
 

Just my experience in using Walbro pumps in recirculation systems. But
to be fair Im pushing a hefty differential pressure through a major
filter bank. With a 6 psid load I only get ~700 hrs. on my Walbro
pumps, I havent measured the amps draw but I wager its 50% of rated amp
capacity.

In article , Doug Dotson
wrote:

Interesting. Can you point me to some supporting docs that
indicates the WALBRO is not suitable as a primary pump.
This is counter to all I have heard from numerous sources
including reputable marine service outfits. Actually, the
WALBRO docs that come with the pump includes only
instructions for installing it as a list pump.

More below.

Doug
s/v Callista

"Rich Hampel" wrote in message
...
Instead of parelleling electrical lift pumps, better to install a 'day
tank' that is constantly supplied by freshly filtered fuel oil but with
a lock-out cock (to an inverted dip tube in the day tank) so that the
day tank always keeps a full load of fuel. Then if you have electrical
failure or filter blockage you will be able to use the 3 or 4 gallons
in the day tank to keep moving and make repairs, etc. If worse
becomes worse, you can always siphon fuel from the main tank(s) and
manually load a gravity feed 'day tank'.

Not practical in my case.

FWIW ... A Walbro IMHO is NOT a constant duty delivery pump.

Not my understanding. This pump seems to have been used for many
years as a primary fuel pump and seems to have a very reputation.

A better
solution for that application is simply an automotive 12v impulse fuel
pump. The Walbro is an intermittent transfer or recirculation pump;
but, can be so piped that if the engine mounted diaphragm lift pump AND
the inline priming pump BOTH fail then the recirculation pump can be
used to either pressurize the system or deliver to the 'day tank'.

That is sort of what I have now. Engine mounted mechanical lift
pump with the WALBRO ahead of it. WALBRO can be used
as a backup in the case of a failure although some plumbing
has to be moved to bypass a failed mechanical pump.

Parallelling fuel pumps --- better to use a 'day tank'
 

Just my experience in using Walbro pumps in recirculation systems. But
to be fair Im pushing a hefty differential pressure through a major
filter bank. With a 6 psid load I only get ~700 hrs. on my Walbro
pumps, I havent measured the amps draw but I wager its 50% of rated amp
capacity.

In article , Doug Dotson
wrote:

Interesting. Can you point me to some supporting docs that
indicates the WALBRO is not suitable as a primary pump.
This is counter to all I have heard from numerous sources
including reputable marine service outfits. Actually, the
WALBRO docs that come with the pump includes only
instructions for installing it as a list pump.

More below.

Doug
s/v Callista

"Rich Hampel" wrote in message
...
Instead of parelleling electrical lift pumps, better to install a 'day
tank' that is constantly supplied by freshly filtered fuel oil but with
a lock-out cock (to an inverted dip tube in the day tank) so that the
day tank always keeps a full load of fuel. Then if you have electrical
failure or filter blockage you will be able to use the 3 or 4 gallons
in the day tank to keep moving and make repairs, etc. If worse
becomes worse, you can always siphon fuel from the main tank(s) and
manually load a gravity feed 'day tank'.

Not practical in my case.

FWIW ... A Walbro IMHO is NOT a constant duty delivery pump.

Not my understanding. This pump seems to have been used for many
years as a primary fuel pump and seems to have a very reputation.

A better
solution for that application is simply an automotive 12v impulse fuel
pump. The Walbro is an intermittent transfer or recirculation pump;
but, can be so piped that if the engine mounted diaphragm lift pump AND
the inline priming pump BOTH fail then the recirculation pump can be
used to either pressurize the system or deliver to the 'day tank'.

That is sort of what I have now. Engine mounted mechanical lift
pump with the WALBRO ahead of it. WALBRO can be used
as a backup in the case of a failure although some plumbing
has to be moved to bypass a failed mechanical pump.

Parallelling fuel pumps
 

The internal filter on the Walbro can be cleaned. In fact, they supply
a spare with the pump. Taking the pump apart is a little fussy in an
emergency situation. I am a little concerned to find out that a pump
failure may result in a blocked fuel supply due to the wobble plate.
Right now, I have the Walbro in line with my mechanical pump.


On Mon, 12 Apr 2004 17:55:34 -0400, "Doug Dotson"
wrote:

I seem to recall from the WALBRO docs that the pump is not
field servicable. Specifically, it states that the internal filters
cannot be changed.

Doug
s/v Callista

"Kelton Joyner" wrote in message
. ..
Unless you have isolation valves to allow servicing of a parallel pump,
series works just as well for backup.
fuel wil flow through the unpowered pump.
Kelton
W4IND
s/v Isle Escape

Larry W4CSC wrote:
(Steven Shelikoff) wrote in
:


That begs the question why are you going to put two pumps in parallel if
you only want to run one at a time?

Steve



Backup?

Larry W4CSC