[T3] Fuel Pump Relay - 69 Fastback

Tim Schiller schillertim at comcast.net
Sat Jul 10 14:35:20 PDT 2021 

The red/black wire (all red on my car) appears to be in very good shape. Since it is all red running through a black outer casing, I’m assuming it was replaced. I’m the 3rd owner of my car. The original couple purchased at Riviera Motors in Portland and after 32 years sold it to their mechanic who had it for another 15 years when I purchased. It doesn’t surprise me that it may have been replaced.

I still removed, cleaned at battery and cleaned & checked all connectors at main power relay. Car still no start. Since I have a couple new relays I replaced power relay just to rule out. That did not fix either. I did not cut the outer casing/sleeve to confirm the entire wire is good.

Since the electronics on the car are so sensitive, I wondering if the problem could be the battery. The car cranks over without problem, but I checked the resting voltage and I get a reading of 11.87. My understanding is it should be 12.6 or higher. My boat battery is closer to 14.

Before I buy a new battery, is this a possibility?  I will put on charger to see if I can get it higher, if only to test this theory.



Sent from my iPhone

> On Jul 9, 2021, at 9:14 PM, William Jahn <willjahn975 at gmail.com> wrote:
> 
> No problem . If you find you need a relay this one would work just fine.
> https://www.autozone.com/electrical-and-lighting/relay-and-resistors/p/novita-40-amp-spdt-accessory-replay/849395_0_0.
> 
> 
> Wouldn't hurt to have a spare and it has all you need and can be mounted
> easy. Still I feel it's that one wire.
> 
>> On Fri, Jul 9, 2021 at 9:07 PM Tim Schiller <schillertim at comcast.net> wrote:
>> 
>> It’s hard not to run out right now and check all those, but will early
>> tomorrow morning. Thx for some direction
>> 
>> Sent from my iPhone
>> 
>>>> On Jul 9, 2021, at 8:58 PM, William Jahn <willjahn975 at gmail.com> wrote:
>>> 
>>> Last thought , if you find there is an issue with the power relay I
>> think
>>> Jim may have some good used ones or just a 30 amp Bosch relay wired the
>>> same way will work , they all work the same way. It's just the amperage
>>> that differs.
>>> 
>>>> On Fri, Jul 9, 2021 at 8:52 PM William Jahn <willjahn975 at gmail.com>
>> wrote:
>>>> 
>>>> 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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>>>>>> 
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