----- Original Message ----
From: Bill Edwards <wpedwards@hilgardhouse.com>
To: lml@lancaironline.net
Sent: Wednesday, May 16, 2007 3:37:18 PM
Subject: [LML] Re: Continental Engine fuel Sys.
Hi Charlie:
Thanks for the good information here. I was struck with a comment you made in an earlier post that TSIO's shouldn't need the electric fuel pumps except in emergencies. Both your and Lancair's manual states that it is necessary to turn on the low boost above 10,000 feet. My engine starts to stumble without the boost at about 12,000 feet in fact. Were you talking about the high boost? Or, have I got something of the same problems described here?
After a long, high altitude, flight, my engine stops running on the runway after pulled to low idle for landing. (So does the other IVP here on the field) If I leave the low boost pump on, it not only continues running all right, but when the mixture is pulled for shut down continues to run as well. I'm sure this is a vapor lock problem and not part of this discussion, but the other IVP has tried everything from insulation to an extra naca duct without success. It seems simple enough to just use the low boost pump, but this discussion made me wonder if there is a deeper problem.
Regards,
Bill Edwards
441JH
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net]On Behalf Of Charlie Kohler
Sent: Tuesday, May 15, 2007 6:17 PM
To: lml@lancaironline.net
Subject: [LML] Re: Continental Engine fuel Sys.
Hi Eugene,
I went back and reread your initial post and I feel you were correctly analyzing the problem.
There is a remote possibility that the vent system is at fault--however it is hard to believe that both tank vents would be plugged at the same time.
If you remove your fuel cap and put a rubber line into the naca vent and blow on it--you should feel air coming out the fuel cap. If not-you probably have a flex line kinked. If you've been flying a while without problems than it's not likely that the vents are too small.
If all is good here--you have to believe something is wrong with the fuel system. That consists of three components. Engine-driven fuel pump/fuel control (throttle valve)/fuel manifold valve.
To have to use the electric fuel pump to keep the engine running below 10,000 feet is indication of a problem and I would not fly the airplane until I found the problem. You are using your emergency backup system in a normal operation.
You don't say how many hours or years on the engine. But if these fuel system components have over five years I would consider them due especially with the problems you are having.
Charlie K.
.
----- Original Message ----
From: "marv@lancair.net" <marv@lancair.net>
To: lml@lancaironline.net
Sent: Tuesday, May 15, 2007 12:06:18 PM
Subject: [LML] Re: Continental Engine fuel Sys.
Posted for "glong2" <glong2@netzero.net>:
Charlie:
I did the check yesterday. I drained about 1/5 quarts through the sniffle
valve and did not get a drop from the manifold valve drain. I was surprised
how fast the high boost pump put gas in the manifold to the sniffle valve. I
am still looking for a better explanation than I have!
Have you ever seen a bad manifold valve diaphragm be intermittent?
This is all good troubleshooting information, thanks for your input.
Eugene Long
Lancair Super ES
"""
Actually-- It's a good hangar "floor" preflight check. There are two
drains-usually on left side by the nose gear door (sniffle valve on the
right).
One, ( the engine driven fuel pump) may drain oil or fuel-- depending which
seal is leaking. Fuel is especially bad as it is a precurser to fuel leaking
by the oil seal and
filling the crankcase.
The other drain is the one in the previous post. The fuel manifold drain.
Another bad (grounding) sign.
A blue stain on the belly or a spot on the hangar floor is a sign.
By the way-- a black (oil) spot on ground under sniffle valve on hangar
floor is a indicator that intake valve guides are worn. If you pull an
intake pipe, you'll find oil inside. Time to think about a top o'haul.
"""
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