Date: Mon, 15 Jul 2019 19:02:20 -0700
Reply-To: Rick Cooper <rickdcooper@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rick Cooper <rickdcooper@GMAIL.COM>
Subject: Re: Throttle-on running issue
In-Reply-To: <1213332725.1738004.1563241046579@mail.yahoo.com>
Content-Type: text/plain; charset="UTF-8"
I've used the technique mentioned by Rich of blowing air back into the fuel
tank to clear debris clogging the outlet. I've done it a few times
successfully and it has allowed me to delay installing a new tank.
However, Chris did not mention fuel pump whining loudly and that was always
present in my case. The other symptoms matched my experience as does
Richard's comment about the problem being worse later in the day after the
fuel has warmed up.
Another possibility is the Throttle Valve Switch, see Bentley p. 24.58.
Rick
On Mon, Jul 15, 2019 at 6:38 PM Richard Koerner <rjkinpb@sbcglobal.net>
wrote:
> Sure sounds to me like a clogged fuel tank outlet. Others have suggested
> using a plastic tank of gasoline into fuel pump to confirm this problem,
> though I'm not clear on how to rig all of this up. Another approach
> (temporary) is to add a 3 foot section of fuel line, blow HARD into it to
> dislodge the crud at fuel tank outlet; I've never done this, nor have I
> ever heard of anyone doing it, but in theory it makes some sense.
> Of course, a whining fuel pump will indicate that fuel pump is
> cavitating....causing fuel line to be full of bubbles, which is of no use
> to injectors. So if your fuel pump is not silent, I think the clogged
> outlet is your problem. Our vans are ancient; even if garaged 100% of the
> time and always kept mostly full of gasoline (like I did with mine), you
> won't escape this problem. Better to do at home than 2000 miles away on a
> road trip (speaking from experience).
> Another clue about clogged fuel tank outlet is that in morning, when
> gasoline in tank is nice and cool, the problem will be less than later in
> the day when gasoline has warmed up. Gasoline vapor pressure issue. Those
> bubbles....hence the stumbling.
>
> Anyway, if you've never replaced your fuel tank, you will need to do it
> sooner or later anyway, and it might solve your current problem.
>
> Rich
> San Diego
>
> On Monday, July 15, 2019, 6:07:10 PM PDT, Chris S <
> szpejankowski@GMAIL.COM> wrote:
>
> I searched first and could not find.
>
> We have a 2.0 ABA with 1.8 head with Digifant II FI.
>
> The engine will start fine from cold. As it warms up it will stumble on
> throttle. Press throttle open - Baaaaaaaaah - nothing. Lift throttle,
> returns to idle, sputters a bit like it’s missing, but then continues to
> idle fine at normal speed. Crack throttle open gradually and it may catch
> the first time, but then baaaaah, until you lift. The hotter the engine,
> the worse it is.
>
> I’ve found no vacuum leaks in intake. Unplugging O2 sensor makes no
> difference ( a new sensor is on the way just in case). Unplugging Temp
> sensor only raises idle slightly, but no difference. I changed fuel pump
> and fuel filter with my new spares, no difference. I swapped AFM, no
> difference. Spark Plugs are recent.
>
> My son mentioned some stumbling issues when it was raining hard, and
> current issue appeared after he filled up with gas. I added gas dryer, but
> no difference.
>
> Ideas?
>
> Chris in atnaltA.
>
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