There’s no provision in the circuits for those relays I’ve seen for generating an initial priming pulse. If you do get one, likely to be spurious triggering from the coil.
T Thanks and that is what I thought. I'll set it up again tomorrow and if it does not work I'll send it back under warranty.
You crank.. and immediately it sees a firing pulse, it should close, a fraction of a second after starting cranking. No need to worry about priming..
Thanks Mike. However, the engine will start and after a short while (say 20seconds) it will cut out. It has done this three times. If I swap back to a direct feed pump to the coil, i.e. relay not connected, the engine runs fine. So it suggests the relay is not activating my fuel pump and the engine is dying through lack of fuel.
In my old set up, yes with ignition only on, but not once the engine is running and I've never crawled under the van to listen. With new set up, no pre-prime as you mention so no, I can't hear the pump. 20 seconds was a guess, could be much longer, I'll time it tomorrow. I don't have a fuel pressure gauge I could check for the short period it runs on the new set up. I could ask my wife to crank the engine with the new set up and having previously disconnected the fuel hose into a large container and see what happens. Sounds a bit dodgy.
Petronix dizzy. @77 Westy mentioned that this relay would not work with a 123 but should be ok with a petronix style.
Would probably depend on the dissy/module. A 123 won’t do anything, as it waits until the engine’s turning over before triggering sparks. Same possibly applies to a Pert II. A Pertronics I might do, as it’s pretty basic. An Accuspark will merely burst into flames…
That’s not quite what I said, or not what I meant if I said it. The relay should work with any ignition with a coil and with a simple electronic or points distributor it might provide a prime. It will also work with a 123 ignition as soon as the distributor rotates but it won’t prime just by turning the ignition on. I use a 321 906 059 C relay and it has worked perfectly for years. https://ratwell.com/mirror/www.dolphinsci.com/relay.html
Ah, I’ve just re-read that as well. You do misunderstand @77 Westy . The relay will work with any dissy/coil setup. What we were talking about was whether it would provide a (spurious) priming pulse.
So ... should the relay be activated, at least for a bit , as long as the rotor spins regardless of distributor as the coil will pulse on the neg at each 'spark' Sent from my SM-G960F using Tapatalk
Sorry for misunderstanding...no slur intended @77 Westy...honest . At this moment in time the hope for a priming pulse is low down in my list, I'd just like it to work!
Yes, as soon as the rotor turns and there is a pulse from the coil the relay will activate and it will stay activated until the rotor stops.
Or use a diode from the alternator light wire and a diode from the starter motor spare tag to create a voltage for a simple four terminal relay which comes on when you crank and stays on once the engine is running. My guess is that the 20 seconds on time of the electronic relay is an ignition-on priming timer, and its not seeing big enough pulses from the Pertronix to keep retriggering on ignition pulses - the coil voltage on points hits maybe 300-500 volts.. with an electronic switch .. 123 or Pertronix or Accuspark etc, the IGBT switch that replaces the points will tend to protect itself by "clamping" the voltage around 100 volts.. should be enough to trigger the coil pulse pin... but the fancy relay has probably been damaged by now by inadvertent mis wiring..
Thanks guys I have checked all of the connections and they are as shown above. I also checked fuel flow on cranking and no fuel is coming through. So I guess it is off to Halfords. Having done some internet research into relays, how they work and options, to the point that I'm possibly not such a huge numpty as I was, but that is debatable, I don't think I need a changeover relay (5 pin) rather, as mentioned by one if you, a simple 4 pin make/break type. But do I need a one with a diode to protect stuff? If it makes any difference to the choice, I'm doing this to reduce the drain on my coil which I think a make and break 4 pin set up will do. From a safety point of view I can only imagine extra safety if the relay is off until the engine is cranking and so stops the pump in a crash that stops the engine. So question 2, does a make/break relay connected to a coil activate on ignition or on cranking? Finally, I intend to also add a fuel cut off solenoid into the mix next to stop any gravity flow. But that is for a later date. Big thanks as ever
