CORRECT Electric Fuel Pump for Aircooled motors

[retrovan]

So it wouldn't be possible to prime your carb before starting?

Best for this would be a push button, so that you do not forget it on the "on" positing, because if you leave it on it makes the whole safety useless.

Herman

[73type2]

That's what I thought the "momentary on/off" switch was.

[Pine]

Or wire it with a relay to you starter so that you prime it at the same time you crank it?

[Tony Z]

Thanks for everybody's input,...........but I am not closer to an answer that makes me sleep better.

Tony,....NC relay coil connected to Oil light ?...........sort of get it. --) relay passing "live" feed through 30 to 87 to pump running. Oil light comes on circuit.......coil kicks in and pump stops.....????

"Switch wired to fuel pump" ???.........don't get this one ?

You guys have done this inyour sleep a thousand times,......so please be patient and very clear.

Regards Haans

OK, lets see what I can do to help and keep it simple.

Get what is known as an 87a relay, this has an extra contact as in picture below


So when there is no power to the relay, 30-87a is closed (Normally Closed - NC) and 30-87 is open (NO)

Wiring circuit 1:
Fused 12V positive goes from fuse bank into 30 - ensure this 12V positive comes from a fuse that only receives power when the ignition is ON (if it is a permanent supply, then the fuel pump will continue running when the car is parked with keys out of the ignition)
87a goes to fuel pump positive
fuel pump negative goes to chassis

Wiring circuit 2:
Connect jumper to oil pressure indication light (takes 12V positive from light when light is on)
Run this jumper into 85
connect 86 to chassis

Result - when oil light is ON, relay opens 30-87a and stops the pump. When oil light is OFF, fuel pump runs.


Optional addition to wiring circuit 2:
add in a NC momentary switch (opens when you push it) anywhere between the oil pressure light and the chassis on the 85-86 circuit.
This cuts the power from the oil light getting to the relay and thus allows the pump to start if the ignition is on but the engine is not running


Does this help?

[Haans]

Tony,.....YES!!!!!! We are now on the same page thank you! You ran with the numbers on the relay ,....and that I can relay to !,,
Thank you,...
Now I take if I decide to add a fuel cut-off valve into the picture ,...it must be "sortoff" added to the oil circuit,....ie oil light comes on,...cutoff operational.

Thank you. Haans

[german]

Not sure if its gonna work. Your oil light is 12v ign and burns when it is earthed. When oil light is on you got earth on 85 and 86.

[Haans]

Geerman,....if you not sure?,........what are you refering to,....the intended fuel-cutoff? ,......or what Tony explained ?
Or are you just messing with our fragile mind ?

Regards Haans

[retrovan]

German is completely right.

You will have to supply permanent power to the relay and only introduce earth from the oil pressure switch when the engine is not running.

You can not take it from the other side of the oil light as that is permanent live when the ignition is on

Thats why its easier to fit a relay on the roof light switch that opens a contact that cuts power to the fuel pump when you open the door to get out.

This solves all the other problems with the other option.

When the cars on fire, you will get out the car in a hurry.

Problem solved.........

Herman

[Haans]

No! ...No Just as I think I have it ,...then youguys mess it all up!&$@€~<<_

Noow just slow down,..... here is what I think I know:

Ignition on : live supplied to 30 through to 87a,....then 86 connected to oil pressure unit on the engine ,..the wire that goes to oil light,..and when this oil light is on (ign still on) the power to 86 will cut the power to pump via 30/87A in the relay

Car starts,....oil pressure valve(sender) cuts earth,...and light goes out,....and poweris restored to pump via 30/97A.

Now what are you guys saying ??.

Haans
What are you guys saying to me?

[Haans]

Are you talking about the cut-off valve ??
Haans

[Tony Z]

Thanks for everybody's input,...........but I am not closer to an answer that makes me sleep better.

Tony,....NC relay coil connected to Oil light ?...........sort of get it. --) relay passing "live" feed through 30 to 87 to pump running. Oil light comes on circuit.......coil kicks in and pump stops.....????

"Switch wired to fuel pump" ???.........don't get this one ?

You guys have done this inyour sleep a thousand times,......so please be patient and very clear.

Regards Haans

OK, lets see what I can do to help and keep it simple.

Get what is known as an 87a relay, this has an extra contact as in picture below


So when there is no power to the relay, 30-87a is closed (Normally Closed - NC) and 30-87 is open (NO)

Wiring circuit 1:
Fused 12V positive goes from fuse bank into 30 - ensure this 12V positive comes from a fuse that only receives power when the ignition is ON (if it is a permanent supply, then the fuel pump will continue running when the car is parked with keys out of the ignition)
87a goes to fuel pump positive
fuel pump negative goes to chassis

Wiring circuit 2:
Connect jumper to oil pressure indication light (takes 12V positive from light when light is on)
Run this jumper into 85
connect 86 to chassis

Result - when oil light is ON, relay opens 30-87a and stops the pump. When oil light is OFF, fuel pump runs.


Optional addition to wiring circuit 2:
add in a NC momentary switch (opens when you push it) anywhere between the oil pressure light and the chassis on the 85-86 circuit.
This cuts the power from the oil light getting to the relay and thus allows the pump to start if the ignition is on but the engine is not running


Does this help?

Not sure if its gonna work. Your oil light is 12v ign and burns when it is earthed. When oil light is on you got earth on 85 and 86.

OK, German is correct, I forgot about that.
Thank you for correcting me

OK, to correct my post
do all as I said, but connect 86 to the same fused power source as the fuel pump. Or even better, connect 86 to the same power source as the speedo cluster/oil light supply
Job done


The way it is wired now, the relay does not have to activate for the pump to run. It only activates when the oil light is on and thus, should the relay fail, you can still drive.

Herman talks about connecting it to the door light, which is fine, it wont run when the door is open, but if you close the door, it starts again. You need another control circuit to ensure it doesnt start up again.
No-one ever talks about the stock engine setup being unsafe, heck that pump is mechanically connected to the engine, so when the engine stops, the pump stops. So if that is safe, why isnt it safe when you wire it up to do the same, but electrically?

Ignition off, pump stops. Engine stalls, pump stops... seems logical to me.

As for the fuel shut-off valve. This is something you want to operate (valve opens) at any point that the fuel pump runs. So plug it in parallel to the fuel pump wiring. Or get a second relay, wire it in exactly the same and connect it to the shut-off valve

[Dawie]

One could also use the fuel pump relay from a k-jetronic car. VW part number 321 906 059. This is a special relay for this purpose. Other injection types's fuel pump relays are just plain universal relays and will not work.

Circuit from link on Tony's page:

[retrovan]

..........
No-one ever talks about the stock engine setup being unsafe, heck that pump is mechanically connected to the engine, so when the engine stops, the pump stops. So if that is safe, why isnt it safe when you wire it up to do the same, but electrically?.....

Must disagree with you Tony with total respect...

VW ' s used to burn to the ground with mechanical fuel pumps before electrical pumps where commonly used in the after market.

No system is worth its cost if you do not fit an fuel shut off valve.

WHY...

Because all pumps are flow through, so as long as the tank level is higher then the lowest point of your fuel pipe, it will run out and keep feeding the fire till the tank is empty.

I have seen as many child conceptions in Drive-Inns as I have seen fires in drive-inn where aircooleds are concerned. Why,,, because the tank is so much higher when standing on the drive-inn mount, that any leak will be twice as bad and on startup , woofe, the car burns.

If your fire has started and is burning, no electrical switch system without a shut off valve will stop the fuel running into the engine bay thus keep the home fires burning.

What I am trying to say, fit the relays but for goodness sake , fit a shut of valve electrically looped from the fuel pump, they not expensive and probably cheaper then the whole relay system.

So whats a shut off valve look like, and where can you get it, well all after market alarm installers have them and they fit them as anti hi-jack systems to stop the car a few km from the crime scene.

Photo of my bay setup


OMO

Herman

[Haans]

I typed out the whole response,....and then it dissappeared into thin air,....so here goes again !!

Thank you everybody !.........but as I am sitting here I don't know what the hell to do,....extremely confusiing.

Dawie,..thanks your pic fron Tony seem to be the most simplistic,...I have two questions

The coil is now fed from pin1 from the relay ?
The feed from the ignition to what was the coil,..is now to go to pin 15 on the relay ?
The feeds from batt to relay and then to pump seem to explain itself.

Talk to me please Haans

[Dawie]

Pin 15 from ign switch still feeds coil directly as before. (Not shown in this picture, it would go to contact on coil marked "15").

Basically the pump control circuit as found on fuel injected cars are built into this relay.
Normally this circuit would be part of the electronic injection controller.
But original basic K-Jetronic is an all-mechanical/hydraulic pressure-controlled system, minus an electronic controller. Therefore the need for a special relay.

When ignition is switched on, signal from pin 15 triggers the relay for a short while. If no signal from points side of coil (terminal marked "1"), is received within a second or 3, pump switches off again. Once engine starts moving, points makes contact, this triggers relay to switch. Whenever engine stops, no alternating signal received from points/coil, for more than a few seconds, relay switches off.