snips...
I take it the problem(s) have been fixed?
Doc Custer
Retired Software Engineer and sometime Audiologist
------------------------------------------------
I don't think the suck air problem has been fixed.
Probably what they did in the Focus was to change the
baffles in the tank. The MSD and Walbro pumps have the
same problem. I found if the intake was 8 or 10 inches
above the fuel level they would not prime.
If you have your pumps higher than that it would be a good
idea to put a one way valve on the intake hose so the
pumps will keep fuel in them when the power is shut off.
I suspect the retail price on these stock Mazda pumps are about
$400 each. Don't know for sure. That makes them a bad candidate.
In that case I would go for a Mallory or Holley positive
displacement low pressure gerotor pumps that have no sucking
problems at around $180 each from Summit Racing The Holley 125
has a built in pressure regulator that saves another $100 to $200.
Summit has a generic pos displ pump for $85. Looks exactly
like a cheap Holley version. Probably both made in China.
Tracy sells a Walbro high pressure AN fitting pump for $121 plus
extra money for adapters that is about the same size and shape as
the Mazda pump. Tracy mentioned the sucking problem. These are
probably available in auto parts stores under the Walbro brand name.
There are however quite a few airplanes flying with these.
MSD has a high pressure AN fitting pump for $104. See the attached
jpg. Flow at any pressure is directly proportional to voltage so it
looks like I don't have to do it :) This appears to be the hot tip.
Paul Lamar ...No rotor no motor.
Are you considering using this high pressure pump for your low cost EFI?
If so, why the switch away from the low pressure PWM pump?
I am confused. Why not put the low pressure PWM pump in the fuel tank with a
baffle? If you run out of gas, you are going down and the loss of a
relatively cheap pump is inconsequential. I think I would rather have two
low cost pumps rather than one expensive one. Maybe I am wrong. That would
be a first -- not! :)
Has anybody looked inside the Focus gas tank? If not, maybe I can get
grandson Dave to scrounge a Focus fuel tank from the junk yard, open it up
and see what is inside. Might even get a usable pump. :)
Doc Custer
Retired Software Engineer and sometime Audiologist
-----------------------------------------------------
I was keeping the options open Doc. The pressure could
be PWM high or low. A higher pressure has a few advantages.
Smaller holes giving more of a spray effect. We need to do
a bit of experimenting regarding the best pressure to use.
The Focus pump is high pressure just like any other car now
a days. Those low pressure pumps could disappear any day now.
I doubt a high pressure Focus pump is any cheaper than an MSD
pump both being near identical.
Paul Lamar ...No rotor no motor.
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