Date:         Tue, 19 Jul 94 00:38:41 CDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Joel Walker <JWALKER@ua1vm.ua.edu>
Subject:      Re: Failing Fuel Pump?

On Mon, 18 Jul 94 23:21:56 CDT Bart Cannon said:
>The weirdness continued.  Twice more the van failed to start, even with the
>fuel pump connected to the ignition and working.  Both times, a whack on
>the the coiled got her started.

the digifant check says:
Fuel Pump Electrical
- Battery fully charged.
- connect ammeter to fuel pump in series with power supply to fuel pump.
- remove fuel pump relay, bridge terminals 30 and 87 with tool US 4480/3.
* Ammeter readings should be approximately 2.5 - 3.5 amps.

lower readings may indicate poor ground.
higher readings may indicate dragging pump motor, pump must be replaced.

now, they don't show a picture of that damn tool US 4480/3, so i don't know
what it is. and there are two power relays in that little black box on the
leftmost firewall (right by the coil). one or both of those might be in bad
shape, or maybe just need the contacts cleaned up.

wiring check for power supply relay:
- switch on ignition.
- check terminal 86 of power supply relay with voltmeter; should read
  battery voltage.
- check terminal 87 of power supply relay; should also read battery voltage.
- if not, remove power suppy relay. check terminal 30 for battery voltage
  (on socket, i guess) and terminal 85 for ground. if both are okay, replace
  power supply relay.

fuel pump relay (my guess at the culprit)
- check terminal 86 of fuel pump relay for battery voltage; check terminal
  30 for battery voltage.
- remove fuel pump relay and check terminal 85 (in socket) for ground from
  3 of ECU while cranking.
  if not: check continuity of wire from terminal 85 of fuel pump relay holder
  to terminal 3 of ECU. if continuity is ok, replace ECU.
- reinstall fuel pump relay. turn ignition off and then back on; check
  terminal 87 for battery voltage (battery voltage will only be indicated
  for about 5 seconds after switching on ignition).
- if voltage is present, check the continuity of the wires from terminal 87
  of relay to fuel pump, and from fuel pump to ground.
  continuity ok: replace fuel pump.

system check with volt/ohmmeter
voltmeter
to terminal  components              checks                  specifications
1 and 13     * wiring from starter   * voltage at terminal   cranking
             * starting injection/     50 during cranking    voltage
               enrichment

3 and 13     fuel pump relay         * ignition on           fuel pump runs
bridged

13 and 14    power supply relay      * ignition on           battery voltage

and the definitions
fuel pump relay - when energized by power supply relay and grounded by
                  ECU, provides battery voltage to fuel pump. location:
                  right side relay inside black plastic relay box, directly
                  above ignition coil on left side of engine compartment.
power supply relay - when energized by ignition switch, provides battery
                  voltage to ECU, injectors, idel stabilization control
                  unit, fuel pump relay, oxygen sensor heater element,
                  and power steering pressure switch. location: left side
                  relay inside black plastic relay box, directly above
                  ignition coil on left side of engine compartment.

all this is from 'Vanagon/Type II Fuel Systems', part # WSP 521-148-00,
which i ordered from my parts dept (cost about $30). it's a spiral bound
service manual (but more for real mechanics with the right tools than a
shade-tree) about the three bus fuel systems, AFC (1980-1983), Digijet
(1983-1985), and Digifant (1986-1991), found in the Vanagons.

hope it helps.
joel