lml@lancaironline.net Mailing List Archive

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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