rjcthree
Well Known Member
Setup - RV-9A, O-320, standard tanks, andair fuel valve, 40108 pump, andair colator, engine driven fuel pump, ellison TB, this then feeds fuel pressure transducer and primer solenoid.
when the odd behavior occurs(keep reading), I've had 5G in left, 3G right (fresh 100LL), 12.5 volts. Master, pump on, when it run normally, it hits 5psi. If I let it sit and run the pump, after a few minutes it starts getting a little louder and within 15 seconds it's clacking away like it's dry. During this time, the fuel pressure falls to zero over 10 seconds or so. It will stop immediately if I hit the primer or drain some fuel from the colator. I can repeat this cycle regardless of tank. I don't know if more fuel or less fuel would change the behavior. I can say it definately clacks if I forget to turn fuel on!
Other tidbits: Plane/hanger temp is 45F. Engine not yet run. Fuel flows at level flight condition on just the electric pump have been in excess of 25G/hr from either tank. I have checked, snugged, sniffed, etc., and can't find any leaks of hints of leaks. Fuel is everywhere it should be, and nowhere it's not.
Running the epump with no fuel flow for minutes on end is not a likely scenario. I'm wondering if the pump is self heating to vaporization and then trying to pump against vapor? Could this just be me asking it do do something that makes no sense?
I'd appreciate if anybody has any insight, I'm about to do first engine start, and don't want to have added complexity of that. I'm considering changing the pump on principal.
Thanks in advance, Rick
when the odd behavior occurs(keep reading), I've had 5G in left, 3G right (fresh 100LL), 12.5 volts. Master, pump on, when it run normally, it hits 5psi. If I let it sit and run the pump, after a few minutes it starts getting a little louder and within 15 seconds it's clacking away like it's dry. During this time, the fuel pressure falls to zero over 10 seconds or so. It will stop immediately if I hit the primer or drain some fuel from the colator. I can repeat this cycle regardless of tank. I don't know if more fuel or less fuel would change the behavior. I can say it definately clacks if I forget to turn fuel on!
Other tidbits: Plane/hanger temp is 45F. Engine not yet run. Fuel flows at level flight condition on just the electric pump have been in excess of 25G/hr from either tank. I have checked, snugged, sniffed, etc., and can't find any leaks of hints of leaks. Fuel is everywhere it should be, and nowhere it's not.
Running the epump with no fuel flow for minutes on end is not a likely scenario. I'm wondering if the pump is self heating to vaporization and then trying to pump against vapor? Could this just be me asking it do do something that makes no sense?
I'd appreciate if anybody has any insight, I'm about to do first engine start, and don't want to have added complexity of that. I'm considering changing the pump on principal.
Thanks in advance, Rick
