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Message
Ooops! On that last message I forgot to delete
Scott's signature and put in mine!
Lee
"Q-Tip" Metcalfe
N320WH
- IO320 - 472 hrs. - Kansas City (IXD)
Grayhawk:
Thanks for the suggestions. This has really got us
stumped.
Blocked screen? (fiberglass shards clogging filters) - All screens
checked, filter changed
Fuel supply line too small?
(nah!) -
All lines checked for blockage (It flew fine for 472 hrs. before prop strike
tear down)
Fuel pressure adequate? (pump problem, try with
boost on)
- Tried with boost on and off, no
change
Throttle body adjusted properly? - Fuel servo and
flow divider bench-tested good
Injectors clogged? - All injectors
checked & flowed OK
Fuel shutoff valve completely
open? - My
fuel system can pull directly from any tank through 3/8 lines, checked all
positions, no problems
Mixture control moves from stop to
stop? -
Checked mixture and throttle control rigging, good to
go
From the first time we ground ran the engine after reassembly the
fuel flow gauge (actually a pressure gauge) has indicated 0 flow
(pressure). The first thing we did is check the orifice fitting at the
flow divider, which was clear. Then we pulled the MAP/fuel flow guage and
had it tested - no problems. Since it ground ran fine up to 2300 (brakes
won't hold it above that!), we decided to try a take-off ( I have the luxury of
a 7400' runway). It accellerated smoothly through about 2400 and was
pulling strong. As I passed through about 3/4 throttle it started to
roughen up and lose power. EGTs (JPI EDM-700) started climbing
rapidly. We aborted, but as we were taxing back to the FBO I realized I
hadn't turned on the boost pump for take-off (my A&P kept screwing up my
checklist flow and I missed it!). So we tried another take-off with the
boost pump on and experienced the exact same
thing.
We flow and pressure tested the electric pump and found that it is
only putting out about 50% of spec so we have a new pump on the way (should
arrive today). But what we can't figure out is, even if the electric pump
is bad, why couldn't the mechanical pump provide the necessary
pressure? My A&P thinks the problem with
the electric pump is preventing adequate flow to the mechanical pump or the
mechanical pump is also bad. Both theories seem a little improbable to
me.
We'll find out this afternoon, I
guess.
Scott Krueger
Sky2high@aol.com
LNC2
N92EX IO320 Aurora, IL (KARR)
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