Mine's also a 2ltr LHD, originally with Weber 34 ICTs and this is the pump and regulator fitted by John at 81a to help with fuelling issues. The Webers have been replaced with Solexes but I've retained the regulator. The pump is a noisy little beggar so I've mounted it on rubber bobbins, still audible but much reduced and at acceptable levels.
I used VW/Audi part number 321 906 059 C (Lucas FDB510 is similar).https://ratwell.com/mirror/www.dolphinsci.com/relay.html
There should be a filter between the tank and the cut-off valve and you’ll probably have to use hose, connecting everything with pipe isn’t easy and you definitely need a hose to the carbs due to vibration, but don’t use SAE J30 R6 hose as shown in your pic.
I ran a relay off the coil.. caused me some grief with signal to electronic ignition that @mikedjames found with a box of magic wizardry and flashing stuff. . I now go relay off the alternator blue for fuel while running, another relay off starter signal for fuel while cranking and a cheeky little wire to run pump from engine bay while tinkering... I might add a shut off too if I can fit it under the back... Sent from my SM-G930F using Tapatalk
I like to keep it simple. No cut-off valve, no pressure regulator, no double relay, no by-pass switch just a filter and pump supplied by one relay.
Mine runs off the Blue wire, pump and shut off. I have a prime button but never need it unless I run out of fuel.
Why do you need a relay compared to an ignition live to the pump and cutoff solenoid? The problem for me with the blue wire/alternator feed being used to switch the relay is that in the event of alternator failure the fuel pump won't work.
A fuel injection pump relay doesn’t use the blue wire, it is triggered by pulses from the coil. When you turn on the ignition the pump starts – on fuel injection this pressurises the fuel rail, on carbs it fills the float chamber – after a few seconds the pump stops until the starter motor cranks the engine, then the pulses from slowly rotating distributor trigger the relay. If the engine stalls pulses from the coil stop and the pump stops whether the ignition is on or not. When you use an ignition live to the pump and cut-off solenoid if the engine stalls and the ignition is on the pump keeps running. Manufacturers try to avoid this for safety reasons. Imagine being rear ended with significant damage to the engine and personnel injury, you could have fuel being pumped over a hot engine– it happens. When it’s easy to use a fuel pump relay for the fuel pump it seems a sensible thing to do but of course a simple connection to an ignition live will run the pump.
That's my kind of wiring diagram Thank you for that. So the relay has a timer function in it presumably to allow carb priming? Is there a modern one that's easily available that does the job? None of them seems to say how long the initial prime is though - do you know if they vary? I found this one https://www.eurocarparts.com/search...wtjmHqacZE5_YRlbUR5PCxt1hLjzVrAhoCJlsQAvD_BwE
Is it OK to put the live feed to the cutoff solenoid in series with the pump? Or shouldo it have a separate ignition live feed. Just wondering how the relay would affect it.
There’s some here from £3.61 to £33.08 https://www.bestpartstore.co.uk/321906059c-oen They do vary and for carbs it would be nice to have one with a longish initial run time – unfortunately I don’t know which one that would be. You might want to connect the cut-off valve to the ignition feed so the valve is open whenever the ignition is on, but it should work okay through the relay opening when the pump runs.
That looks like it will do the job. And it's German . Much better than using a feed from the alt to determine whether the engine's running. I assume these things generate an intial priming/pressurising pulse to the pump, which is then retriggered by ignition pulse once the engine's running. I wouldn't think you'd need the cutoff valve any longer, as no fuel should pass when the pump's not running.
