[T3] Fuel Pump Relay - 69 Fastback

[William Jahn]

On the positive battery post there is one red/black wire that runs across
from the battery pos to 30/51 on the power relay . That wire is fastened to
the pos battery clamp  bolt by an eyelet then the battery clamp nut . This
wire is the only power to the power relay . Check that to make certain it
has a good connection to the battery . If there is a voltage loss there you
will not get 12 volts at the pump relay . All it takes is it being loose or
corroded . It runs all the way from the battery to the power relay. That
may explain why it works then doesn't. That is the contact part of the
relay that sends power to 85 on the pump relay. If it's loose or corroded
all it takes is to try to start the car and you get an arc which might be
just enough for it to make enough contact to run the pump . I would check
that before going any further. If there is going to be a bad connection
either it's loose and you know how battery cables get corroded . It's
simple to check and rule it out . It runs near the top inside of the wall
held by small tabs . You will be able to see it easy.

On Fri, Jul 9, 2021 at 8:01 PM Tim Schiller <schillertim at comcast.net> wrote:

> Replaced fuse with 8 amp just in case it was bad. Bentley manual shows
> most fuses are 8 amp except 9 & 11 are 16 amp. Appears several mine are 16
> when they should be 8. Separate issue.
>
> I hear the 2 clicks, both the fuel pump relay a main power relay when key
> is turned on.
>
> I tested pump again with a direct power source and it buzzes. Car actually
> started a ran for a while after immediately hooking relay back up. However,
> when I turned it off it would not start again. When car was started, the 87
> pin was reading 12V
>
> Back to testing the fuel pump relay. The voltage to pin 87 is not
> consistent. Turning key I sometimes get a zero reading, sometimes a 5-6V
> reading and sometimes a 2-3 V reading. I tested when the pump wire was not
> attached trying to eliminate the ground wire to the pump as a possible
> issue. Not really sure how anyone can follow that brown wire between relay
> and pump.
>
> I found some help to turn key so I could hold on to pump. There is a
> little bit of a buzz when the key is turned on, but didn’t seem that
> strong. It feels like it is priming or buzzing for 1-2 seconds when the key
> is then turned off. Seems just opposite of what it should be doing
>
> Currently trying to find something on Samba forum for a similar problem. I
> really struggle with the search function on Samba
>
>
> Sent from my iPhone
>
> > On Jul 9, 2021, at 12:39 PM, Jim Adney <jadney at vwtype3.org> wrote:
> >
> > On 9 Jul 2021 at 10:48, Tim Schiller wrote:
> >
> >> I will follow the ground and check the fuse
> >>
> >> I did hook a reliable 12V to the red wire going to pump. Pump buzzes
> loud
> >> and clear.
> >>
> >> I had purchased 2 relays and swapped just in case one was bad, but same
> >> results
> >
> > One other quick check you can easily do if the car is in a quiet place,
> is to
> > listen when you turn the key ON. You should hear a relay click when the
> key
> > goes ON and a second relay click about 1 second later.
> >
> > If you have questions about whether this is happening correctly, look
> under
> > the back seat, on the  driver's side. Mounted on the top rail, there
> will be 2
> > relays, each mounted with a single screw. One of them has a ground wire
> > under that screw head. Make SURE that screw is tight. That's the ground
> for
> > the main power relay coil.
> >
> > --
> > *******************************
> > Jim Adney, jadney at vwtype3.org
> > Madison, Wisconsin, USA
> > *******************************
> >
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