Date: Wed, 3 Aug 2016 13:43:25 -0700
Reply-To: Neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil N <musomuso@GMAIL.COM>
Subject: Re: Bucking/Loss of power on HOT days
In-Reply-To: <1469972996.11314614.1470249544070.JavaMail.yahoo@mail.yahoo.com>
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On my '81 with Jetta 2.0, a similar thing happened. The fuel pump has
always been prone to being noisy ( new at time of swap as was tank etc.)
but would always get louder on hot days especially if climbing a
steep grade for any amount of time.
On a trip through a desolate area, with my fuel pump screaming away, I
pulled over, let engine idle. It sputtered and died. It felt like vapour
lock. It wouldn't start so I pulled the gas cap and heard a "whoosh" of
air. With cap off, engine started. On a spare gas cap, I removed a little
material to help allow tank to pull in ambient air. Not sure if this helped
but no more stalls. I swapped in a used charcoal canister after that and of
course reinstalled the other gas cap.
AKAIK, my fuel pump hasn't been that noisy since.
My swap uses the Jetta charcoal canister purge valve which is
quickly cycled open closed by the ECU. Does the obd1 Suby swap use a
similar valve?
At one point I wondered if my different purge valve system pulled more air,
over a given period of time, than the OEM design. i doubt it though. Even
if it did, the charcoal filter should vent to atmosphere right?
On my swap the fuel hoses likely pick up heat in engine bay but then I have
to imagine that the WBX fuel hoses being so close to the engine case, would
also allow fuel to pick up heat.
OTOH, I can't recall if the WBX return hose is above the WBX engine.
I'd be curious to see how your Suby swap would work with a fuel tank having
the 12 mm outlet.
Neil.
On Wednesday, August 3, 2016, Richard Koerner <rjkinpb@sbcglobal.net> wrote:
Am having bucking and loss of power on very hot days.
> My van is an 85 2WD (233,000 miles), manual tranny, with a 2.2 Subie
> engine (recent conversion by California Westys in San Diego), .....
> The symptoms are classic "vapor lock"; yes, unusual with pressurized fuel
> delivery on fuel injected engines, but I've been going through the List
> Archives and there have been cases resembling vapor lock.
> Typically, everything runs fine at freeway speeds in hot conditions; the
> bucking problems start when I pull off freeway and have to contend with
> stoplights and idling and low speed.
>
> This has happened at low elevations but hot (Florida and Laughlin, Nevada)
> and also at high elevations (Gunnison, Colorado) on a warm summer day.
> Problem disappears when van is allowed to cool overnight; starts fine and
> runs fine the next day.....until it gets hot outside and van is moving slow.
>
> Mild whining (not screaming) from fuel pump when this happens. I suspect
> some cavitation and pump damage occurred. Anyway, I've replaced fuel
> pump....
> Other things I've read about include: gas cap, charcoal cannister, bad
> coil, fuel pressure regulator, bad ignition coil.
>
>
--
Neil n
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