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Steve,
The pump I have from NAPA has an obviously hand inscribed Walbro number in the area under the rubber cover. It may be worth checking that to try to verify the pump identity and flow rating. It may also be worth checking the flow rate of the individual and both pumps by capturing the fuel where it returns to the tank.
Steve Boese
> On Mar 24, 2017, at 3:19 AM, steve Izett <flyrotary@lancaironline.net> wrote:
>
> Hi Guys
> Hi Peoples
>
> Here is a photo of our parallel pumps plumbed with 3/8 aluminium lines feed from a 28 gallon header tank above to the right.
> Fuel then passes through the firewall and race filter before feeding the rail and returning via the pressure regulator (4cyl toyota reg)
> back through the firewall to the header tank, again in 3/8.
>
> I did further measurements today.
>
> 1. Bottom Pump only ~8A and 48psi - Turning both pumps on this pump draws 9.9A and produces a rail pressure of 65psi
> 2. Bottom Pump only ~9.9A and 44psi - Turning both pumps on this pump draws 14.8A and produces the same rail pressure of 65psi
>
> So bottom pump goes from 8.0 -> 9.9A (1.9A increase) under higher head pressure
> Top pump goes from 9.9A -> 14.8A (5.1A increase) under same head!!
>
> Clearly Pressure Reg bypass capacity is inadequate for both pumps, perhaps with even one pump running.
> (I don’t have data of fuel pressure under load to see if it drops as power is applied)
> I think I modelled the pump layout/manifold after seeing someone else’s and not sure if it causes any problems?
> The pumps came from eBay stating that they were genuine Walbro and now I’m wondering.
>
> Cheers
>
> Steve Izett
> Glasair Super II RG Renesis 4 port RD1C EC3 EM3
>
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> <Fuel Pres Pumps.JPG>
Fuel Pres Pumps.JPG
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