[T3] Fuel Pump Relay - 69 Fastback

William Jahn willjahn975 at gmail.com
Fri Jul 9 20:52:49 PDT 2021

From what you said I doubt if the pump relay is the issue. I bet you find
that red /black wire at the battery is either loose or corroded or the
eyelet on the end of that wire is not making good contact to that wire. If
it's not there check the spade connector on the power relay. It has to be a
good connection at both ends. If it is that red/black I would still make
sure the power relay spade connectors are all sound and fit snug . I went
through mine a while back and found the brown ground screw was fine yet the
spade connector only had one rolled edge . It worked I was just checking
and happened to find it. So I checked them all . it's even possible the
power relay contacts have high resistance yet they don't have that much
current to burn them. Mine is the original on my 73 I decided to just check
for voltage drop and found there was some so I removed the relay cover and
cleaned the contacts. This is my only car and the last thing I want is to
be sitting somewhere stranded.

On Fri, Jul 9, 2021 at 8:34 PM William Jahn <willjahn975 at gmail.com> wrote:

> 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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