in the link it says it is a replacement for the VW part number 321 906 059K. I am not sure what the difference is between the C and the K though. When I called VW and GSF they told me it is discontinued. Don't mean to confuse just trying to get people some options if they want t get hold of one. I am considering it but currently have the system posted by Dave Whippy.
Terminal 2 Normally closed to ground-Opens at 2-5 PSI Terminal 1 & 3 Normally open-Close @ 2.5-9 PSI Wells 3 pin oil pressure switch M10x1.o thread £6.....(Transporter '79 and Campmobile stock part) Bosch 4 pin Relay £4 http://www.how-to-build-hotrods.com/electric-fuel-pump.html
possibly....you'd normally just rig it up to the warning lamp....check to see what the VDO requires voltage wise
Resurrecting this thread, I tested out a theory this morning regarding my engine's cold start reluctance compared to my hot start; crank once and she fires. I disconnected my fuel pump +ve feed from my coil and temporarily connected to the battery to test if the electric pump was drawing too much power. Lo and behold, the camper started much easier from cold on a very damp morning. Now to find this fuel pump relay - 321-906-059C (VWH not is stock and £40) or an equivalent. Thanks to @snotty for his advice on wiring as well. Any help in finding a relay that has a short prime function for the carbs would be gratefully received!
Thats where the 2 relay solution comes in basically the second priming relay closes the priming pushbutton and is triggered by power to the solenoid on the starter. Then you have the main relay driven off the alternator. In this way you are just using 1 or 2 stock Halfords 4 terminal relays, nothing fancy. Or you can use 2 diodes. And yes, you can also connect a fuel shutoff solenoid to the fuel pump power. Many electric pumps like the Carter have a sealed in ball bearing and spring acting as the pressure relief valve so their pressure is fixed, but because they have constant flow, they dont suffer the wierdness of the fuel pressure from a worn demand valve style dead-headed regulator eg. Malpassi going high at very low flow. FI systems always use a pressure relief system because its hard with a demand valve style to keep e.g 42psi when the pump winds up to about 120psi at zero flow. Also the circulating petrol is cooling the pump and FI pipelines. Carter style rotary pumps also do not suffer from pressure drop like a Malpassi, if you do not put enough pressure in, the output pressure has to drop some to open the demand valve, which could be the cause of some stories of fuel starvation with big engines. Also if you get some dirt in or wear of the Malpassi it could basically end up doing nothing, as at zero flow it leaks pressure through.
I use a timer relay to trigger the fuel pump relay. It turns the pump on for about 20 seconds when you turn on the ignition. This gives enough time to get the engine started & for the alternator to energise & keep the pump relay on. There are several methods of wiring the pump but for safety reasons it’s not a good idea to have it directly wired to an ignition feed. https://www.ebay.co.uk/itm/CAR-TIME...2349624.m46890.l49286&mkrid=710-127635-2958-0
I am at the edge and pushing beyond my electrical knowledge with this, but learning fast. I was hoping for a single, simple and safe relay to take power off the starter and the signal from the coil and if possible prime the carbs first, I think that's right anyway! I am not sure how important the priming is for twin Weber 34icts, so this may not be needed and I think a few cranks of the starter will prime them anyway in the unlikely event the floats are empty. I'll look into these options you guys suggest whilst still searching for the unicorn relay
Tried Euro Car parts for the relay? Both myself and @Mark Darby (?) got one from there, but we may have got the last two . You won’t find one that provides a priming pulse (although if you get your soldering iron out, you could make it do it). You can live without the fancy relay, as the chances of the cutoff feature ever being used are minimal (hopefully). In the meantime, just keep cranking…
You might have, if I could figure out how to get past Eurcarparts interface that does not recognise my reg, nor allows me to see the parts without a 'valid' number...aaaagh Edit, sorry that aaaagh is not directed at you, but at my lack of knowledge and lack of relay
It is a really annoying site, I agree. Snotty is right, we got the last 2. Somebody else was looking shortly after us and they seem to be unobtainable now. Probably simpler to go for the two relay option with two bog std relays.
Thanks. Is there a simple connection diagram anywhere here that does not involve a push button primer (which I'd rather avoid) and a really BIG arrow pointing me towards these two relays that are in stock somewhere....yes I know that's spoonfeeding, and my ego has long gone so pretty please
Thats what we went for one switched by starter one by alternator . Plus a noisy cupboard bypass to check pump still works or priming after messing about Sent from my SM-G960F using Tapatalk
Hasty rework I did once of someone else's so might need a sense check.... ditch the last 87a connection if you don't want a primer... and any old 5 pin changeove relay will do https://www.halfords.com/tools/fuses-electricals-and-fixings/electricals/halfords-hef557-relay-12v-30a-5-pin-184161.html?cm_mmc=Google PLA-_-Tools>Fuses, Electricals and Fixings>Electricals-_-Tools>Fuses, Electricals & Fixings>Electricals-_-184161&istCompanyId=b8708c57-7a02-4cf6-b2c0-dc36b54a327e&istFeedId=62b447cf-331e-4fec-a47a-9985ff72d404&istItemId=axtta&istBid=tzwt&_$ja=tsid:94971|cid:8979078227|agid:94446562487|tid:aud-863531155855la-369985451494|crid:412800844949|nw:g|rnd:11080331045105965528|dvc:c|adp:|mt:|loc:1006963&gclid=CjwKCAjw87SHBhBiEiwAukSeUcxlbPusKY2Lfujec8B0PRRcKfohFDPpvYByZye3KTqJMK4OU_QsZxoCkt8QAvD_BwE
Thanks. I was just looking over some old diagrams to try to figure this all out. Can I just check why two relays, one to the starter solenoid and one to the alternator? Is that an either/or situation or do I need both? If I'm understanding the layout, they both seem to be doing the same job if I ignore the push button. Happy to learn if I've got that completely wrong. Thanks
The alternator relay only let's the fuel pump run with the engine running, the starter one makes sure you get fuel while cranking in case your fuel bowl gets a bit low from standing. Sent from my SM-G960F using Tapatalk
This should work, one relay, five wires. It might provide a prime pulse but not with a 123 distributor. https://www.autodoc.co.uk/topran/2723347
Cheers all. @77 Westy I had seen that one but because of the lack of information about it passed it over. I'll try that and see. If that one does not work I'll go down the double relay route @Deefer66. As ever, thanks
There’s plenty of relays for fuel injection systems that should also work for low pressure pumps. My 321 906 059 C (liberated from a scrapyard many years ago) primed the carbs with the Accuspark distributor but doesn’t with the 123. Relay terminal connection should be: 15 Coil + (15) 30 Fuel Pump + 31 Ground- 31b Coil - (1) 87 +12V