get a Noid Light at a FLAPS.
I never bother with resistance checks on the AFM........but they are there
in Bentley.
what I find happens with AFM's is the get 'uneven' ............and, it's
fundamentally a weak area - it's where electronics interface with mechaical
contact and movement - always a basic weakness.  Modern cars don't have an
AFM with moving parts or contacts. They use another principal to get infor
about how much air is going into the engine, so the ECU knows.

tricks on AFM's include bending the arm inside so it rubs on a new contact
area. There are rebuilt ones, and there are new ones.
I have run 6 used AFM's back to back on a good running 1.9
wbxr..........only on of the was pretty 'even' .......all the rest ran
'lumpy'..........unevenness of acceration.  I think the waterboxer fuel
injection is *slightly* inherantly uneven in power delivery thourgh the
gears anyway ............though my 85 Wolfsburg Weekender with full 2.1
waterboxer fuel injection, and auto trans...........isn't 'uneven' while
accelerating at all.  M7y 83 Westy, with 2.1 and 1.9 fuel system is
slightly..........but I havn't tried a new AFM on it either.

I forgot if this is a 1.9 . ( I forgot until below it's an air-cooled ! )
if it is..........where the ECU gets its single from the
distributor/ignition is very distinct and easy to locate.
On the Ignitor on the firewall, left side there...........there are about 6
or 7 wires going to the ignitor plug.
One of them is white.
this white wire, is the ONLY connection between the ignition system and the
ECU on a 1.9 waterboxer.  That's the wire the ecu gets that info through.

on the 2.1 its fully integrated as, the igniter function is inside the ECU.

the ECU sees the engine is turnng via the igntion system.
to fire the injectors it doesn't actually need the AFM signal.
if you install the AFM and air box, but acciedently forget to plug in the
AFM......it'll start and run. It'll even drive around weakly, or hold back,
then rev out well at full throttle, but it won't run right.
AFM signal is not an absoute requirement for the ecu to fire the injectors.
oh........shoot...........
I could look in the Bentley I suppose - I try 'not to' know much about
air-cooled vanagons !
there may not be a throttle position switch or switches. Sorry to mislead
you there !

Sounds like you are understanding it pretty well about the fuel pump relay.
and yes..........all cars have something, to shut off the fuel pump if the
engine stalls, but the key is left on.
In yours it's the AFM signal that keeps the fuel pump relay energized I
think.
when it's running again.........I think you'll fiind if it's running, and
you intentinally stall it in gear, ( but keep the key no ) the fuel pump
will not keep running.
Great that you're getting into it deeply.
You'll have it figured out pretty soon I think.
scott

----- Original Message -----
From: "James Bradley" <beer_eighty@YAHOO.COM>
To: <VANAGON@GERRY.VANAGON.COM>; "Scott Daniel" <scottdaniel@TURBOVANS.COM>
Sent: Wednesday, October 08, 2008 9:26 AM
Subject: Re: Technical question re: Injector firing signal

> First, I will track down a noid light. Never heard of one untill this
> morning.
>
> I had tested my AFM previously, I will recheck again to my abilities.
> I'm just checking for resistance values, yes?
>
> I replaced the temp sensor II about three weeks ago.
>
> "The ECU  has to see the that the engine turning - it gets that from the
> distributor/ignition system.
> throttle position switch"
>
> I'll have to look into this, unsure how to test but I am getting spark to
> all cylinders and my hall sensor generator tested ok per Bentley.
> Does ECU see ignition is turning or AFM is taking in air???
> Where is the signal sent to the ECU from distributer???
>
> I dont believe I have a TPS on my aircooled.
> But I did re-track my AFM about the same time I replaced the temp sensor.
> ( i lightly bent the control arm to an untouched part of the signal track)
>
> " and the ECU triggers the fuel pump relay."
> (?? doesnt the AFM trigger this??)
> "Does the fuel pump run for a few seconds when you turn the key to 'on' ?"
>
> I have fuel pressure (36psi) but not at key on
> At "key ON" ONLY the injectors, terminal #10, & AFM #39 (which eventually
> powers the fuel pump) have energy.
> Fuel does not pump untill turn over, energized from the second relay, then
> AFM#39 takes over ONLY when there is air being drawn in the intake (safety
> shutoff, or fuel would pump in an accident, right?)
>
> I fell a bit confused now,
> Some clarification please