Fuel Lines

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Fuel Lines

 

 

 
Dcp01454.jpg (87641 bytes) Looks so easy...
The tube is bend with several angle, going down and sideway out of the center console, coming back forward at the fuselage side and then, forward down at the fuel pump level.
Dcp01456.jpg (105298 bytes) ... but I needed to practice a bit
I bought a roll of copper tubing from the local hardware store to make sample parts.  It took me quite many trials just to get the first two bends right.
Dcp01455.jpg (94757 bytes) Quite good result
One thing I believe is important with the routing of fuel lines is to avoid "low" areas.  My fuel line goes "up" at the pump and then "up" again at the valves.  It will get out of the console straight and go "up" again to the boost pump on the firewall.  Then it will go "down" to the gascolator.
Dcp01457.jpg (83669 bytes) A view of the fuel pump installation
The pump is installed on the first nose rib at about 45 degrees (as specified in the instruction manual for the pump).  The rib is reinforced with a channel riveted to the other side.
DCP01855.JPG (94560 bytes) Ouch... interferences
I initially installed the firewall fuel pump in front of the brake pedal.  Not good.  The parking brake valve is also not properly installed and the bend in the cable is too tight.
DCP01957.JPG (50493 bytes) Talking about not good stuff
Initially, the fuel line from the front pump to the gascolator was installed like this.  My mentor did not like that as he says that I should reduce the length of line behind the radiator (in warm air).  I then installed a 90 elbow and a new line coming straight down.
DCP01974.JPG (48741 bytes) Way to go!
DCP02049.JPG (97912 bytes) Fuel pump test
I tested my three fuel pumps and they work find and noisy.  Especially when pumping air.  I get more than 25 gal per hour of fuel flow from each pump.  Even the firewall pump which is pretty high (12" from the floor") has no problem priming itself up from the tank on the floor.  Each pump will put about 3 to 4 psi of pressure (at 11.9 volts from the battery).  When I turn on the firewall pump with a wing pump, the pressure comes too high at around 9 psi.  I may put a switch cover on the firewall pump switch.
DCP02048.JPG (99489 bytes) Fuel pump check valve test
I checked how much gas was flowing through the system in the opposite tank.  Well, there is a leak.  The fuel pump has internal check valves, but they are not perfect.  I tried putting a check valve in series with the fuel pump and the result is worse!  Instead of about 0.5 to 0.8 liter per hour, I get 3 to 4 liter per hour of cross-transfer.  This may be explained by the fact that two check valve in series somewhat cancel their capabilities (there is no flow to push the ball or diaphragm in the check valve).  I removed the check valve I put in there (and had to replace a segment of fuel line).
   
   
   
   

 

 

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