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Subject:Fuel system "vapour lock"
From:Neil N
Date:Tue, 12 Aug 2014 15:15:44 -0700

Hi all. I'm out of town using a slow internet connection so did not search
the archives.

If the EVAP charcoal canister is plugged (saturated?), or the vent hose at
canister is plugged, can this cause the EVAP system to create a vacuum in
the fuel system? Or, is there another potential cause? Is checking the
canister a simple matter of blowing through the tubes? The "why" is below.
Thanks, Neil.

 On a hot day, after climbing a steep grade in 2nd gear to a high altitude
on a long forest service road, I pulled over, left van idling. Over about
5 seconds the idle dropped, got uneven, engine stalled. It wouldn't restart.

Removed fuel tank cap, heard a sucking noise at filler tube. The tank had
obviously built up a vacuum. Put cap back on, got engine to start but it
would surge or die. Removed the cap, heard same noise at filler pipe. Fuel
pump was also making a lot of noise. Cap off, it ran fine. Found spare old
cap, removed rubber seal to allow a little air in while driving. Van then
started and drove fine getting me out of a potentially hairy situation.
Left camp today using proper fuel tank cap. It's running fine, no sucking
noise at filler pipe heard when cap removed.

--
Neil n

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