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  1. #46
    Do you ever leave? Mickss355's Avatar
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    The normal way to hook it up is by using the grey tach wire to trigger the safety switch - have you tried this ?
    He who dies with the most toys wins !

  2. #47
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    The grey will be on the 6AL-2. I'm wiring one of them now but will be a little while before it is running.

    The one I'm having issues with is an older 6AL.
    Must be something that alters by using the purple/green trigger as opposed to the white trigger . This setup works sweet with a 6AL that is triggering on the white .

  3. #48
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    I gather the 6AL-2 must be different since it worked for SICKHG as mentioned above .

  4. #49
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    SickHG , what brand LPG switch did you use ??

    Ok I used the Gastec brand switch . It works with a 6AL that is triggered through the with wire .
    NOT with the magnetic green/purple wires .
    I contacted Gastec and this is part of their response . This method works nicely with the pickup signal wrapped tight around a plug lead

    The SD40 will also operate by winding 10 turns of ordinary insulated hook up wire around the high tension lead leading to one of the spark plugs. Keep the coils of wire touching each other (i.e tight together), then wrap with insulation tape to hold in place.

    Make sure you have a stable +12 volts once the engine has started & make sure the earth is very good. If you have any concerns about the earth, wire the earth to the negative side of the battery.

    When cranking, the voltage must not fall below 9.0 volts
    .

    Last edited by Gregaust; 09-02-2014 at 10:00 PM.

  5. #50
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    I use a fuel pump controller from revolution electronics on all the cars I rewire,
    Works on off tacho signal similar to the gas tech, has internal circuit breaker,primes for the seconds on turn on.
    Ran run of msd,CDi,electronic dizzy,points. Unit is fully potted for vibration protection and comes per wired with enough length to get the job done.

  6. #51
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    If your using a VK or earlier then hook from D+ terminal (warning light) on the alternator to 85 on the relay. 86 to earth. 30 to B+. 87 to pump.(same as earlier diagram without all the extra bits). The relay can't engage until the alternator comes online. The relay will open turnning the fuel pump off as soon as the alternator stops.
    with the gas relay almost any tach. signal will trigger it. The ign supply can come from anywhere apart from coil+. Idleup solenoid power supply etc.

  7. #52
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    Quote Originally Posted by Elric View Post
    If your using a VK or earlier then hook from D+ terminal (warning light) on the alternator to 85 on the relay. 86 to earth. 30 to B+. 87 to pump.(same as earlier diagram without all the extra bits). The relay can't engage until the alternator comes online. The relay will open turnning the fuel pump off as soon as the alternator stops.
    with the gas relay almost any tach. signal will trigger it. The ign supply can come from anywhere apart from coil+. Idleup solenoid power supply etc.
    Would need an NC relay to do this or 87a on a C/O relay, or am I not getting this ???

    Shane.

  8. #53
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    Quote Originally Posted by HPEngines View Post
    Would need an NC relay to do this or 87a on a C/O relay, or am I not getting this ???

    Shane.
    If a N/C relay is used then the pump will run when the engine is off so a N/O relay is required. How it works is the charge light is powered from ign. The light globe acts as a current limiting device so the relay cannot engage from having the Key On but the Engine Off (KOEO). The voltage at the D+ terminal of the alternator is 0v.
    When the engine starts the alternator starts charging and a voltage is supplied from the D+ terminal of the alternator. This voltage matches the voltage supplied to the ign. side of the charge light so because there is no potential difference (voltage difference) the light goes out- there is 14v. on both sides of the globe. The voltage from the D+ terminal comes from the exciter diodes in the alternator which power the field circuit in the alternator. With the 85 terminal of the relay hooked to the D+ terminal the exciters will also engage the relay but if the engine stops so does the alternator thus open curcuiting the fuel pump.
    The only issue with this system is it doesn't "prime" the fuel system though the car will start on the fuel in the carby but getting the fuel up the first time means bridging 30 to 87 until the carby is full. If you get evaporation or want to prime the carby as the vehicle cranks simply run a lead from the starter through a diode to 85 terminal. This will engage the relay while the engine cranks and the diode prevents the exciters feeding back to the solenoid- it can't hold the starter in because the exciters can't supply enough current to hold the solenoid in but it would pull the exciter voltage down stopping the alternator charging and damaging the exciters.

    Isuzu used a similar system on the early gemini and rodeos. Many of the Japanese alternators used the Star or Neutral terminal which is connected to the centre connection on the stator and provides half system voltage when the engine is running to trigger a 7v. relay using N/C contacts to turn the charge warning light off when the alternator was charging and N/O contacts to control the fuel pump.

    Sorry doing this on tablet & its a PITA so I have changed to my desktop comp.

    The gas relay is a very good way of controlling the pump but some times the ign systems interfere with them so having a backup idea can help.

    I first came up with the (alt D+) idea back in the late 70's as a way to trigger a twin battery charge system as none of the voltage sensitive relays/DCDC converters were around in those days & the diode packs were rubbish.

    I always liked the system on the gemini's as when they dropped an alt. the car would stop so we could just go hook the fuel pump to the tail lights to get it back to the workshop. The battery would still be charged so simply o/haul the alt. & it went straight away. With most vehicles they were driven until the battery was dead flat then the owner wanted the thing in an hour. We could do the alt. but we couldn't charge the battery in that time & they would never put it on a charger overnight as instructed then !@#$ & whine when the battery dropped dead early.
    Last edited by Elric; 03-10-2014 at 09:40 AM. Reason: high tech devices that need a low tech solution-size 12 boot ;)

  9. #54
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    Quote Originally Posted by Elric View Post
    If a N/C relay is used then the pump will run when the engine is off so a N/O relay is required. How it works is the charge light is powered from ign. The light globe acts as a current limiting device so the relay cannot engage from having the Key On but the Engine Off (KOEO). The voltage at the D+ terminal of the alternator is 0v.
    When the engine starts the alternator starts charging and a voltage is supplied from the D+ terminal of the alternator. This voltage matches the voltage supplied to the ign. side of the charge light so because there is no potential difference (voltage difference) the light goes out- there is 14v. on both sides of the globe. The voltage from the D+ terminal comes from the exciter diodes in the alternator which power the field circuit in the alternator. With the 85 terminal of the relay hooked to the D+ terminal the exciters will also engage the relay but if the engine stops so does the alternator thus open curcuiting the fuel pump.
    The only issue with this system is it doesn't "prime" the fuel system though the car will start on the fuel in the carby but getting the fuel up the first time means bridging 30 to 87 until the carby is full. If you get evaporation or want to prime the carby as the vehicle cranks simply run a lead from the starter through a diode to 85 terminal. This will engage the relay while the engine cranks and the diode prevents the exciters feeding back to the solenoid- it can't hold the starter in because the exciters can't supply enough current to hold the solenoid in but it would pull the exciter voltage down stopping the alternator charging and damaging the exciters.

    Isuzu used a similar system on the early gemini and rodeos. Many of the Japanese alternators used the Star or Neutral terminal which is connected to the centre connection on the stator and provides half system voltage when the engine is running to trgger a 7v. relay using N/C contacts to turn the charge warning light off when the alternator was charging and N/O contacts to control the fuel pump.

    ... wow
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  10. #55
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    Sounds good , must sus this out . My Gastec ones are working well.

  11. #56
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    Quote Originally Posted by Gregaust View Post
    Sounds good , must sus this out . My Gastec ones are working well.
    just had a look back on the thread. Gregaust if your using an MSD 6AL then it should have a tach signal plug on the end of the module. Its a place to plug in not a wire comming out like the leads to the coil etc. You can connect the "tacho"wire from the gas relay to that & the ign supply to the thin red wire on the MSD unit.
    I wouldn't try to use the magnetic pickup leads from the msd unit to try to trigger the gas relay as its used by the msd as an input to trigger the msd unit. The gas relay is designed to be triggered by a directly switched voltage like when the points open curcuit the ign coil. The magnetic pickup is a pulsed voltage generated by a magnet passing a coil of wire. The pulse shape, voltage etc will be completely different.
    Hope this helps

  12. #57
    Part of the furniture bloodycars's Avatar
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    ^^^^^ think we found a new guru for the site. Jeeebus!!!!!

  13. #58
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    Thanks Elric .
    Now with the MSD 6AL what I have found . If the MSD is triggered by the white wire , I.E points then the tacho feed does trigger the gas relay all AOK. Works sweet

    Now if the mag trigger is used with a MSD Billet dissy , the tacho feed does NOT give a good signal to run the gas relay . What happens is the relay feeds power and shuts off , but then immediately switches back on . My theory was there must be some residual current feed there to keep re-switching.
    I think I posted above somewhere what I got from the manufacturer, 10 wraps of normal 4 mm hookup wire around a plug lead gives enough pulse to switch just fine .

    I don't know if the 6AL2 is the same as the normal 6AL as yet .

  14. #59
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    Gregaus I take it you are wanting to use the MSD billet dist. It definitely sounds odd that the tach pickup will work with the "points" pickup but not the magnetic pickup. I think you are correct about the residual voltage. The only thing I can think of is check the earth including the chassis earth. With electronic systems it doesn't take much to upset things & a high resistance earth will play havoc.
    hope this helps.

  15. #60
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    I have already set it all up and is running . One car I have is as I say a points triggered MSD , tach signal is fine . The other with billet dist and mag pickup = no go . It does as I say , switches on, runs/primes and shuts off , then gets obviously a tiny feed and starts up again.
    It is working well using the pulse from the spark plug lead .
    Not too sure yet if the 6AL2 is different , I've not got that one running yet .

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