On any domestic fuel cap, once you remove it, the pressure it released. The
flap has nothing to do with it. If you look closely, you'll see two holes
on either side of the flap and one on the bottom. Those are there for
overflow. And...in case anyone wants to know why that flap is there...it's
for emissions. Same thing with the size of the opening. If you tamper with
the size of the opening (or remove the flap), and the Smog Tech actually
checks it (like we were required to do in the BAR-90 days), you will fail a
"Visual" inspection. The size was made to prevent people from putting
regular (leaded) fuel in their tanks back in 1988.
You can also relieve any pressure in the tank by removing the vacuum line to
the EVAP Purge Solenoid (Big vacuum pot looking thingy attached to the
firewall on V8's and manifold on V6's). Since the EVAP can holds fuel
vapors until the engine reaches Closed Loop (then it purges into the
manifold), you can relieve the pressure this was as well. (Just don't smoke
near the vacuum line when removing it...and NO, I haven't ever done that.)
- Bernd
-----Original Message-----
From: owner-dakota-truck@buffnet.net
Subject: RE: DML: Re: RE: Fuel pressure release valve (Bernd)
'94 and up... :-)
The rationale behind removing the gas cap (and pressing in the flap) is
just to make sure there's no pressure in the tank. While the tank itself
won't usually be pressurized, changing environmental conditions could make
it a possibility (however slight). (Seal up a plastic 5 gallon gas can
some time, come back a while later, and chances are the sides will either
be sucked in or bloated out. Any time a volume is isolated from the
atmosphere, pressure differentials will be created.) Removing the cap
takes no time to speak of, so I take that extra step.
I have released the fuel pressure a couple of ways, including running
the engine with the fuel pump deactivated (actually I don't think there was
even enough pressure to cause the engine to fully start), and despite that,
a decent amount of gas still came out of the fuel test port, so (in my
experience, anyway) running the engine until stall doesn't always remove
all of the pressure (hence the extra steps I mentioned).
YMMV
-Jon-
.--- Jon Steiger ---- jon@dakota-truck.net or
stei0302@cs.fredonia.edu ---.
| Affiliations: AOPA, DoD, EAA, NMA, NRA, SPA, USUA; Rec & UL Pilot - SEL
|
| '92 Ram 150 4x4 V8, '96 Dakota V8, '96 Intruder 1400, '96 FireFly 447
|
`------------------------------
http://www.cs.fredonia.edu/~stei0302/ ----'
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