CKeller
Premium Member
- Joined
- Aug 18, 2006
- Messages
- 268
- Reaction score
- 25
Hola BiplaneForum Peeps -
I thought my Dukes fuel boost pump was giving up the ghost...and choking on the cost to overhaul one of these little gems...when I figured out the pump works properly SOMETIMES and then OTHER TIMES it does not.
"Works properly": throttle cracked 1/4", mixture rich, boost pump ON, I hear it come on and after a second or two, the pump loads up and changes its tone, and I see a fuel flow indication on the pressure gauge in the cockpit. Engine starts normally.
"Does not work properly": throttle cracked 1/4", mixture rich, boost pump ON...pump runs and never loads up (changes pitch), never get any fuel indication on the cockpit gauge. Engine has no prime and won't start.
After troubleshooting this one for a while, I am led to believe that the location of the pump high on the firewall is causing fuel to drain back down away from the pump when the fuel level in the tank is below the pump...the pump does not pump air very well, so it cannot pull fuel up the line and into the pump. Thus, in any situation other than nearly full fuel in the main tank, I get no boost.
It didn't always seem to do this, and I believe its possible the pump has worn internally so its now unable to pull the fuel up to the pump itself. Thoughts on this theory?
Fix: move the pump lower on the firewall, preferably at the same level as the bottom of the tank. It will take a little doing to re-route/re-fabricate fuel hoses, but I can do this. I am convinced this will do the trick. Just wondering where other builders have located their electric boost pump relative to the gascolator/fuel quick drain, fuel valve, fuel tank, and engine driven pump.
I thought my Dukes fuel boost pump was giving up the ghost...and choking on the cost to overhaul one of these little gems...when I figured out the pump works properly SOMETIMES and then OTHER TIMES it does not.
"Works properly": throttle cracked 1/4", mixture rich, boost pump ON, I hear it come on and after a second or two, the pump loads up and changes its tone, and I see a fuel flow indication on the pressure gauge in the cockpit. Engine starts normally.
"Does not work properly": throttle cracked 1/4", mixture rich, boost pump ON...pump runs and never loads up (changes pitch), never get any fuel indication on the cockpit gauge. Engine has no prime and won't start.
After troubleshooting this one for a while, I am led to believe that the location of the pump high on the firewall is causing fuel to drain back down away from the pump when the fuel level in the tank is below the pump...the pump does not pump air very well, so it cannot pull fuel up the line and into the pump. Thus, in any situation other than nearly full fuel in the main tank, I get no boost.
It didn't always seem to do this, and I believe its possible the pump has worn internally so its now unable to pull the fuel up to the pump itself. Thoughts on this theory?
Fix: move the pump lower on the firewall, preferably at the same level as the bottom of the tank. It will take a little doing to re-route/re-fabricate fuel hoses, but I can do this. I am convinced this will do the trick. Just wondering where other builders have located their electric boost pump relative to the gascolator/fuel quick drain, fuel valve, fuel tank, and engine driven pump.
