Date: Thu, 1 Sep 2005 21:21:18 -0700
Reply-To: Tom Young <tomyoung1@COMCAST.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Tom Young <tomyoung1@COMCAST.NET>
Subject: Re: Aircooled Running Problems
Content-Type: text/plain; charset="iso-8859-1"
It sounds like the engine is basically running too rich, which can happen.
Over time the spring in the AFM weakens, giving feedback to the computer
that more fuel is needed at all speeds and temps then is actually the case.
Re-seal the cover on the AFM (you can get "false air" through here) and take
it to someone with an exhaust gas analyzer to have the CO checked.
If it's running too rich you can adjust the AFM via the provided mixture
screw. If the spring has weakened to the point that you can't adjust the
mixure lean enough with the screw then it's either time for a rebuilt AFM or
you go in and tighten the spring in the AFM. (This procedure is
well-documented in the archives.)
----------------------------------------------------------------
Tom Young
Lafayette, CA 94549
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----- Original Message -----
From: "Thompson, Michael" <Michael_Thompson@GOLDER.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, September 01, 2005 6:28 PM
Subject: Aircooled Running Problems
Hi all
I have a strange running problem with my 1981 aircooled westy. The vehicle
starts and runs fine, with correct idle. However, when blipping the
throttle when parked, the engine hesitates as if mis-firing until the RPM
gets high enough and then it revs okay (maybe 3 seconds). When driving,
this is shown as 'hopping'/bucking when accelerating at partial throttle, or
when decelerating at partial throttle. If the throttle is opened wide, the
bucking stops after 2-5 seconds and the engine runs normally on the highway.
In addition, power is down on hill climbs and the fuel milage is a low 14
MPG on a highway run at 70 MPH. All 4 spark plugs have black sooty coating
suggesting rich running, and when the throttle is blipped after idling for
10 seconds black smoke comes from both exhausts (EMPI).
The problem is I have checked/tried virtually EVERYTHING using the
ProTraining Manual and Bentley. The entire ignition system, including
distributor is brand new and timing has just been set. I have checked
everywhere for leaks in the injection system and can find none. I have done
all electricall checks on the AFM and it checks out fine within spec (I even
pulled the cover and everything looks well inside). I have checked the cold
start valve, the fuel pressure (only 1psi above the high end of the
acceptable range), injectors and resistor impedence (9.2 ohms compared to
approx. 7 in Bentley), the head temp sensor is new and I have checked it
electrically as well.
I have not checked the injectors for leaks as all 4 plugs are sooty and I
would be suprised if all the injectors went at once. All I can think of is
the computer, although my understanding is that they are incredibly reliable
and don't go wrong ofter.
HELP PLEASE - I can't think of anything else to check, and I don't have a
spare computer.....
TIA
Michael
