[T3] Fuel Pump Relay - 69 Fastback

Sun Jul 11 16:28:28 PDT 2021

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.

'

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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