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Tue Dec 12, 2017 6:25 am

He he thanks, I'll read up. I think all I am stating is than rather than put the switch on the hot how someone asked it would be beter to put on ground.

dhaavers wrote: ^^^ Sorry to say, but your responses here indicate that you are still working on
understanding basic electrical theory. Please stop before someone gets hurt... :(

Check it: http://www.autoshop101.com/forms/elec11.pdf

- Dave

Tue Dec 12, 2017 6:50 am

If you install your switch in the main current path to the pump you will need a switch and wire rated to handle 8 amps or more, whereas if you install your switch in the trigger circuit for the fuel pump relay you will be dealing with a much smaller current so can use a smaller gauge wire and a lighter rated switch.

Another way to go would be to add a relay in the ground path for the fuel pump. This would allow for a small gauge wire running forward and a switch with a low current rating. It would also be very easy to bypass should the system fail, as all you would need to do is hook the original ground wire back up. If you left the original ground wire in place, but disconnected from the pump, it would only take seconds to be running again.

Tue Dec 12, 2017 6:53 am

Wildthings wrote:

Another way to go would be to add a relay in the ground path for the fuel pump. This would allow for a small gauge wire running forward and a switch with a low current rating. It would also be very easy to bypass should the system fail, as all you would need to do is hook the original ground wire back up. If you left the original ground wire in place, but disconnected from the pump, it would only take seconds to be running again.

This is exactly what I did on my previous bus.

Tue Dec 19, 2017 8:44 pm

dobryan wrote: Wildthings wrote:

Another way to go would be to add a relay in the ground path for the fuel pump. This would allow for a small gauge wire running forward and a switch with a low current rating. It would also be very easy to bypass should the system fail, as all you would need to do is hook the original ground wire back up. If you left the original ground wire in place, but disconnected from the pump, it would only take seconds to be running again.

This is exactly what I did on my previous bus.
Late to the party (been off-grid for a week at Jalama beach. :) ) - and this is also exactly what I did.

A relay interrupting the ground feed for the pump, installed right beside the pump so an easy swap of wires should the relay or its control fail. A small guage wire (again in the ground side) to a tiny slide switch installed in a very inconspicuous place - no, no pics, it's my secret.... :P

OK, it could be foiled by a thief with some electrical savvy, but as it stands it works very well as a kill-switch, but very easily bypassed when in the know. The fact it catches out both myself and Mrs fxr about 30% of the time shows it isn't an obvious thing to engage. ;)

Tue Dec 19, 2017 11:47 pm

Ok, I'll play...
I have this switch interrupting the ground wire directly from the fuel pump.
https://www.superbrightleds.com/moreinfo/installation-supplies/mini-onoff-toggle-switch/1353/3111/
It is rated to 10 Amps. I have been using this switch in this configuration for sometime between 1.5 and 2 years.
I have learned some valid points about interrupting the pump relay instead of the pump itself. If the need arises, I will likely rewire my kill switch. However, I just put my dash back together last week, and while I know i get better at it every time, I'm not inclined to rewire my switch now.
James

Wed Dec 20, 2017 8:47 am

I just posted this is another thread but this is a better place for it.

I like this idea for a hidden switch. With a remote, you have better options where to hide it. Less than $20.
https://www.ebay.com/itm/Logisys-RM02-Wireless-12V...35cb22971e

Wed Dec 20, 2017 9:16 am

I have two Vanagons with switched ground interrupts for the fuel pump.

1. 1983 Westfalia, 16 AWG wire run all the way from ground at the pump to the rear heater fan control switch on the dash all the way back to the chassis ground next to the pump. ~25 ft additional wire in the ground path. Only 1 of the 4 possible switch positions will allow the pump to run. Rear heater was deleted, so this switch was available. Can be bypassed at the pump or at the switch in case of failure. Running 1 year without issues.

2. 1990 tintop, 16 AWG wire run same as above but to a hidden switch. Running 6 months without issue.

Wed Dec 20, 2017 9:47 am

drj434343 wrote:

1. 1983 Westfalia, 16 AWG wire run all the way from ground at the pump to the rear heater fan control switch on the dash all the way back to the chassis ground next to the pump. ~25 ft additional wire in the ground path.

Why not to a local ground under the dash?

Wed Dec 20, 2017 9:59 am

Great ideas, thanks for the input. Being a visual learner, can some kind soul post a simple drawing of how a relay next to the pump and run to a switch in the cab would be wired? I’m sure it’s simple but a picture for us non-EE folks....
I would probably use the generic relay GW sells, think I have one on hand.

Thanks

Wed Dec 20, 2017 10:19 am

pomfritz wrote: Great ideas, thanks for the input. Being a visual learner, can some kind soul post a simple drawing of how a relay next to the pump and run to a switch in the cab would be wired? I’m sure it’s simple but a picture for us non-EE folks....
I would probably use the generic relay GW sells, think I have one on hand.

Thanks

I am wanting to do this soon also, so i sketched up my interpretation

Wed Dec 20, 2017 10:52 am

Thanks Brandon,

On the relay you use the 87 to 30 contacts?

Wed Dec 20, 2017 11:04 am

To wire it proper, the fuel pump would ground through 30 and 87. You could also run power through 30 and 87. It just depends how you want to wire it. If you look at the relay you can see the electromagnet with pins 85 and 86. You would add power to one leg and ground to the other. You would then toggle either 85 or 86. When the relay electromagnet is energized, 30 and 87 are connected.

All of this explained, if you go back and read my posts and compare against the wiring diagram. You don't need to add a relay, you can simply add a toggle to the power relay ground to interrupt the engine running.

Wed Dec 20, 2017 11:16 am

i wonder if it would be more mysterious if the ECU relay was disabled. Vanagon theives, used to Vanagons, may listen for the fuel pump sound with key on just as a natural part of starting one. i do.

either way, i think it is a great feature to add... "Hey, this van doesn't start. Stupid Volkswagens."

-dan

Wed Dec 20, 2017 1:31 pm

Paulbeard wrote: drj434343 wrote:

1. 1983 Westfalia, 16 AWG wire run all the way from ground at the pump to the rear heater fan control switch on the dash all the way back to the chassis ground next to the pump. ~25 ft additional wire in the ground path.

Why not to a local ground under the dash?

I had a length of sheathed 2 wire cable so I really only ran 1 cable. Part of the reason was an experiment; would the added path to ground resistance of that loop affect the pump? The answer after 1 year is that I haven't noticed a difference.

Wed Dec 20, 2017 3:41 pm

Can someone post a link of switches that would work? All I can find in toggle switches etc... are rated inAC not DC.
Thanks

Wed Dec 20, 2017 4:05 pm

pomfritz wrote: Great ideas, thanks for the input. Being a visual learner, can some kind soul post a simple drawing of how a relay next to the pump and run to a switch in the cab would be wired? I’m sure it’s simple but a picture for us non-EE folks....
I would probably use the generic relay GW sells, think I have one on hand.

Thanks
Below is the circuit of what I did. It just needs one wire running from the relay to the switch - wherever you might put that. Here's a link to the switch I used, almost invisible when installed on a black background:

https://www.frys.com/product/1945881

Wed Dec 20, 2017 6:34 pm

candyman wrote: Can someone post a link of switches that would work?...

Almost any ordinary toggle will work fine, rating on most will be much higher than needed (irrespective of whether it says AC or DC).

Or you could use a blank spot in the dash pod for one of these:

https://www.ebay.com/itm/VW-Volkswagen-Vanagon-Rea...mp;vxp=mtr

Wed Dec 20, 2017 6:37 pm

That is how I would prefer to do it. To be clear, the +12 wire is just the existing power wire to the pump?

Mark

Wed Dec 20, 2017 7:20 pm

crazyvwvanman wrote: That is how I would prefer to do it. To be clear, the +12 wire is just the existing power wire to the pump?

Mark
Yes. I cut off the original spade connector to the pump and fitted a new one incorporating an extra wire to go to the relay coil.

Wed Dec 20, 2017 9:28 pm

That’s a really helpful diagram Jim. I am used to using relays switched from the power side, not the ground side.
Thank you Mark and Jim especially for taking the time to clarify all of this.
James