[T3] Fuel Pump Relay - 69 Fastback

Sat Jul 10 18:53:06 PDT 2021

they should read the same even with the battery at a lower standing
voltage. It's a short wire. Any wire will have some voltage drop and the
longer the wire is it will have a certain amount of resistance. from the
power relay to the pump relay is a heavy gauge wire so at the pump fuse it
should read battery voltage. Another possible issue could be the ground
strap from the trans to the frame. All bets are off if the battery is too
low of voltage or has a weak cell. I've sen new batteries when I was a Ford
tech drain overnight. The only way to know if it was a drain was to check
but to be certain I would remove it, charge it then check it the next day.
Batteries can have all sorts of issues.

On Sat, Jul 10, 2021 at 3:51 PM Tim Schiller <schillertim at comcast.net>
wrote:

> Voltage at battery 11.84, voltage at power relay 11.84
>
> Turn key on and voltage at power relay drops to 11.67 Is this enough of a
> drop to make a difference?
>
> Voltage at fuel pump relay (87 pin to fuel pump)when cranking engine is 9
> to 9.8
>
> Sent from my iPhone
>
> > On Jul 10, 2021, at 3:02 PM, William Jahn <willjahn975 at gmail.com> wrote:
> >
> > To know if that red wire is good, do a voltage drop test on it. Find a
> good
> > ground use the battery neg voltmeter black then turn the key on touch the
> > pos battery post then do the same with the voltmeter on the relay where
> the
> > red wire is connected both should read the same , if not the wire is not
> > good. I don't know if the wire is red /black that what the bentley shows
> ,
> > I don't recall on my 73 it seems to be red, at least the part you can
> see.
> > I doubt someone changed the wire and ran it through the sleeve. The
> > important part is the power relay should show battery voltage even if
> it's
> > low . The battery cranks the engine over it should be enough to work the
> > relay. If the battery is old or has a dry cell then that can present
> > issues. Most batteries have a date code on them. There is another wire
> from
> > the starter to the ECU that powers the relay while cranking yet if your
> > voltage is too low just key on that may not be an issue, It runs from the
> > starter to a connector near the left of the engine it's above the engine
> > tin . I just don't   see it on a 69. Try to find out why you don't see
> > battery voltage on the power relay first, don't trust visuals, do a
> voltage
> > drop test. Or if you have a wire you can bypass it. It needs to be at
> least
> > the same gauge larger is ok.
> >
> > The only other thing is the ign switch , it may have an issue because it
> > not only engages the starter it also powers that system once you release
> it
> > . That would also  cause things to work and not work. You may at times
> hit
> > a good spot when it does run.
> >
> >> On Sat, Jul 10, 2021 at 2:35 PM Tim Schiller <schillertim at comcast.net>
> >> wrote:
> >>
> >> 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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