Mailing List lml@lancaironline.net Message #15678
From: <Sky2high@aol.com>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Fuel Cooling
Date: Tue, 08 Oct 2002 18:12:44 -0400
To: <lml>
The question about vapor lock did not mention airplane model or engine type.

In Lancair 320/360s, the cowl area behind the baffling can get hot since there is no air movement there.  One way to help this is with 1 or 2 one inch blast tubes to help keep some components cool when the airplane is moving.  A hot stopped or idling engine can heat soak the engine mounted pump which can cause fuel to vaporize in the pump thus leading to cavitation.  I don't know the consequence with a carbureted engine, but an injected engine can lose important fuel pressure because of the cavitation - the instant remedy is to run the boost pump to keep the pressure up and, perhaps, re-liquify the vapor. 

Injected engine hot starts are very difficult when the above situation occurs.  Of course, if you have an engine with a fuel return line, such as a Continental, you can run the boost pump with the mixture at idle cut-off for a minute or so to use cool fuel to cool the engine pump and return the heated fuel to the tank.

Scott Krueger
N92EX
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