[T3] Fuel Pump Relay - 69 Fastback

Tim Schiller schillertim at comcast.net
Sun Jul 11 16:57:49 PDT 2021


Ground the wire or the pin? I assume the pin

Sent from my iPhone

> On Jul 11, 2021, at 4:28 PM, William Jahn <willjahn975 at gmail.com> wrote:
> 
> you can take the pump wire off the pump relay to rule out the pump being
> the problem , it won't hurt anything. I wouldn' ground the ECU wire. Keep
> in mind the reason there is a fuse for the pump is in case either the pump
> or the wiring from the pump relay to the pump shorts.
> 
> I doubt you have faulty relays since you changed both and it made no
> difference.
> 
> " I was reading out of a Clymer manual and it discussed pulling the wire
> from the 85 pin on the pump relay that I believe goes to the ECU #19. It
> says to ground this wire to Bypass ignition. Says the pump should run full
> time when doing this to test if pump is good " That does not bypass the
> ignition it just grounds the pump relay coil that pulls the contacts closed
> to send power to the pump though the pump relay contacts. 30 and 87.
> 
> When you turn the key, what does it feel like? Is it stiff , does it
> return back when you release the key?
> 
> The reason I ask is because the ign switch the electrical part when you
> start the car it powers the starter and supplies power to the fuse box and
> relays , when you release the key it just powers the electrical to run the
> coil and ECU and headlights and so on. Once you release the key all that
> does is remove power to the starter.
> 
> All I'm getting is it did work a few times and will not most of the time.
> 
> The pump relay 30/51 battery voltage great. 86 fine. 85 is the ground from
> the ECU both 86 and 85 are the relay coil 30 and 87 are the contacts. So
> the power relay is doing it's job or you would not have 13 volts on 30 on
> the pump relay. You can ground 85 as long as you remove it from the pump
> relay and use another ground like a jumper . I never checked if 85 had
> voltage on it because it's a ground and I don't feel it's a good idea to
> check for voltage there and I don't know how much resistance the coil has ,
> it may read battery voltage I just never did that. To not have voltage on
> 87 tells me the ground 85 is not grounding via the ECU so the coil is not
> closing the contact to send voltage from 30 to 87. Try removing 85 from the
> pump relay and ground it. If that works then either ECU is not working that
> ground circuit or there is an issue with that wire from the pump relay to
> the ECU. The mystery is why it did work a few times.
> 
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>> On Sun, Jul 11, 2021 at 3:03 PM Tim Schiller <schillertim at comcast.net>
>> wrote:
>> 
>> Without putting a bigger charger on battery, it is at 13V now. There is
>> also 13V at the power relay.
>> 
>> Thought I would start at beginning at check pump relay again. There is 13V
>> at the 30 pin. When ignition is turned on, there is also 13V at the 85 and
>> 86 pins.
>> 
>> When I check the 87 pins it is pretty consistent at zero. This is true
>> with multiple new relays. If I disconnect pump wire, should I get 13V at
>> the pin? I was just trying to eliminate the pump causing a short.
>> 
>> The negative braided battery cable has some corrosion. I will need to
>> order one if I’m to replace.
>> 
>> Harbor Freight has an ignition bypass to allow starting of car when you
>> can’t fully turn key. Is this the type of bypass you are referring to?
>> 
>> I was reading out of a Clymer manual and it discussed pulling the wire
>> from the 85 pin on the pump relay that I believe goes to the ECU #19. It
>> says to ground this wire to Bypass ignition. Says the pump should run full
>> time when doing this to test if pump is good. Didn’t want to do until
>> asking someone much smarter than I.
>> 
>> I still need to check the ground from the frame to the transmission. I
>> also need to follow the wire from the starter as suggested. How do you
>> follow a wire when it disappears inside the harness and is covered with the
>> rest of the wires?
>> 
>> It seems like the biggest problem is the is no power at the 87 pin on pump
>> relay.
>> 
>> Sent from my iPhone
>> 
>>>> On Jul 11, 2021, at 2:03 PM, William Jahn <willjahn975 at gmail.com> wrote:
>>> 
>>> When I checked mine a while back I unplugged the ign coil . Since this
>>> issue seems to work sometimes and it runs wouldn't it make sense that the
>>> ign switch might be the problem. It seems intermittent to me and they
>> don't
>>> last forever and it's a moving part.  We know it's not the relays he
>>> replaced both with the same result. Seems  since the ign switch could be
>>> the cause. I don't know if 69 has a replacement part.
>>> 
>> https://www.westcoastmetric.com/c-1182978-vw-type-3-1969-vw-type-3-electrical-ignition-switches-harness.html
>>> 
>>> It's just a thought and after what he has already checked and really
>> found
>>> nothing it might be a good place to check . Never tried to bypass the ign
>>> it's possible to do as long as one can use a jumper to pull from the
>>> starter circuit once it starts . Or for the sake of just a test just jump
>>> the battery hot to the run just to see if the pump and relays have
>> battery
>>> voltage could even unplug the coil during the test so it will not
>> overheat.
>>> 
>>>> On Sun, Jul 11, 2021 at 1:34 PM Jim Adney <jadney at vwtype3.org> wrote:
>>>> 
>>>>> On 11 Jul 2021 at 11:21, William Jahn wrote:
>>>>> 
>>>>> When checking for a voltage drop in one wire to the power relay one the
>>>> pump
>>>>> relay times out the only draw on the power relay is the ECU .
>>>> 
>>>> Also, the ignition
>>>> --
>>>> *******************************
>>>> Jim Adney, jadney at vwtype3.org
>>>> Madison, Wisconsin, USA
>>>> *******************************
>>>> 
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