REFLECTOR: Re: Fuel Pump Cooling

[Chuck Harbert]

My understanding of electric aircraft (or high perf automotive) fuel pumps 
is that they are designed to be cooled by the fuel circulating thru them. 
Modern fuel injection systems have a pressure relief valve (prv) that is 
overcome by the electric pump pressure so that cool fuel is recirculated 
thru the pump and back to the tank. This is how my system is setup, and my 
pump is also on the lower engine firewall. The mechanical pump puts out 
about 25 psi, but when you turn on the electric the prv hold the pressure at 
30 psi. Some people install a fuel return line and manual valve at the fuel 
distributor (spider) particularly when it is located above the engine to 
recirculate cool fuel to this vapor lock prone area. It works well for hot 
starts.

Personally, I wanted both of fuel pumps inside the engine compartment such 
that a fire or explosion from a leak would not be in the passenger area.

Chuck H

------------------------------------- 
> I was a bit surprised to see that, too.  I have thought that the fuel 
> boost
> pump is used on a sufficiently "intermittent" basis that cooling would not
> require special consideration.  I was even considering installing the fuel
> boost pump on the cabin side of the firewall.  The pump itself is cooled 
> by
> the fuel passing through it, but that probably doesn't help the electric
> motor driving it.  Has anyone else identified a need for cooling for the
> pump motor?
> Keith Hallsten, XLFG
------------------------------- 
>> Rene
>> I am flying the same engine 260hp. i have not considered any cooling
>> for the electric fuel pump. Mine is located at the bottom of the
>> firewall and as far as I know heat has not been a problem am I
>> missing something
>>
>> -- 
>> Jack Sheehan