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

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

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

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

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

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

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

On Mon, 12 Apr 2004 13:33:26 -0000, 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?

Then I wouldn't put them in parallel without isolation valves. Even if
it works when both pumps are good, you don't know how the pump will
fail.

Steve

That is my concern. I think I will install both check valves
and isolation valves as well.

Doug
s/v Callista

"Steven Shelikoff" wrote in message
...
On Mon, 12 Apr 2004 13:33:26 -0000, 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?

Then I wouldn't put them in parallel without isolation valves. Even if
it works when both pumps are good, you don't know how the pump will
fail.

Steve

Dont need check valves if you install isolation valves.

In article , Doug Dotson
wrote:

That is my concern. I think I will install both check valves
and isolation valves as well.

Doug
s/v Callista

"Steven Shelikoff" wrote in message
...
On Mon, 12 Apr 2004 13:33:26 -0000, 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?

Then I wouldn't put them in parallel without isolation valves. Even if
it works when both pumps are good, you don't know how the pump will
fail.

Steve