where to get power, but only when engine is spinning.

[love ke70]

ok.
i have a 1ggte in a ke70 running a GRA lpg carby.
its not starting.
i have figured that this is because the solenoid on the lpg tank isnt opening (the wire isnt attached to anything)
this wire must attach either directly to a power source to open the solenoid, or via a relay.
either way the problem being that i need a power source from which power is sourced only when the engine is in motion (if not the engine fills with lpg when car is stopped and next time i go to start i should bend over and kiss my arse goodbye before doing so)
so, i thought to myself "alternator" and was like "wow, what a brilliant idea" however i did some probing and couldnt find a wire/the wire that carries a charge with the engine spinning. dont know if my issue is that i can only do this on the starter or if im simply not getting the right wire.

if anyone could help me out on which wire it is on a 1g alternator, or if anyone has an idea on where to get a power source that ive mentioned that would be wonderful

now then, this is a gra carby....so i have no ecu...just so its clear

[oldcorollas]

sound slike what you need is one of those relays that only closes when it is getting spark signal from the coil..

volvos use them and other cars also use them...

if you just use coil power or whatever, still doesn't mean engine is turning over..
if you use an oil pressure sender switch, then it might stay open afterwards (although another relay would help there.... so maybe you could use one of them)

but spark triggered relay is prolly best bet... if engine stops... so does the gas...]

[love ke70]

how do i get spark signal from the coil?

(sorry, never messed with this side of things before)

[mullett]

Jaycar also do a variable-voltage switch-in kit, so you could have the solenoid only open at 13.8v, which the car only produces when it's running. You'd need to rig up something for the starting tho...

RM.

[love ke70]

yer, that could work...
like have it so it opens when the key is turned to start, and also when im getting >13 volts or something.
probably easier if i can grab a wire off the alternator or coil tho.

i assumed the wires from the alternator that charge the battery, unsure of which these are tho, and if they have 0 voltage when the engine isnt spinning or if they are at 12V



:S

[BradW]

You need a tachometric relay ( I think that is what they are called ).
If you go to an lpg installer and talk to them, they should have something that will do the trick.
You could also use the fuel pump relay from an EFI 6cyl VK commodore. It has inputs for ign, crank trigger and tacho pulse. If wired to the gas lock solenoid it will only power it up when cranking or when a tacho signal is present.

[love ke70]

would just a splice from the tacho signal wire be enough to open and keep open the solenoid. or could i use it to close a relay? or would it not hold because its a pulse, not a constant power?
cheers guys

brad, i may look into that fuel pump relay

[-GT-]

Yeah i would've thought that installers would have something they use for when converting cars, much like you need one now They should be able to at least point you in the right direction.

I don't think the 13+V is the simplest way, having to run an extra circuit to get gas to start it makes it sound more complicated. I'm with Brad on the tacho signal, not sure if the pulse signal would be a problem though, to be safe you could run something like the jaycar kit mullet mentioned to switch.

[love ke70]

yeah, see the install did work at some distant time ago. but its been effed around with, and looks like a very bodge way to start with. so im sorta trying to redo it properly and so the car will start.
i like the vk fuel relay idea or maybe see wat a gas installer can offer.
just a thought, where do i get the tach signal from? splice it from the wire that leads to the tacho in the car, or is there somewhere in the engine bay i can take it from?

because at the moment the stock tacho isnt going to work properly due to 4cylinders becoming six so it will over read, although the signal is still getable. hmmm
but yeah, where is the best/easiest place to get tach signal from? ie where does it originate.

ok im rambling, and i think ive made my point so im going to bed

[oldcorollas]

You need a tachometric relay ( I think that is what they are called ).
If you go to an lpg installer and talk to them, they should have something that will do the trick.
You could also use the fuel pump relay from an EFI 6cyl VK commodore. It has inputs for ign, crank trigger and tacho pulse. If wired to the gas lock solenoid it will only power it up when cranking or when a tacho signal is present.

thats the one... and yes, LPG installers should have them. and so should GRA

[love ke70]

so the tachometric relay works just the same as that vk relay?

where do i grab a tach signal from?

and the other 2. ignition, just off the "on" position on the ignition yes?
and crank trigger, take that off the "start" position on the ignition yes?

+ rep to you all, but i need to spread the love more

[oldcorollas]

depends.. i think the volvo ones used signal from the coil.. and held on for about 2 seconds after last pulse.. so the actual rate of firing doesn't matter (as far as dif number of cylinders).. for the VK, it might be from coil or from ECU... most? VK were still carb, but some were EFI, can't remember how it was set up tho.... quick look ta a VK commondore gregories manual in K-mart should do the trick

[SL666]

i think its called a 'gas lock' a mate who used to do LPG installs was telling me because we were looking for a circuit to shut off my fuel pump if the engine isn't running for 3 seconds.

[BradW]

so the tachometric relay works just the same as that vk relay?

where do i grab a tach signal from?

The VK fuel pump relay is a tachometric relay. I think the EFI XF falcons use the same relay as the VK's. Afaik these are not on the carby VK's, only EFI models. These could also be the same as the volvo relay that Stewart mentioned earlier.
Gemini's used a fuel pump relay that ran off the star point of the alternator ( usually the "n" terminal ). Don't know if the 1G alternator has provision for this but it could easily be modified.

Tacho signal on the VK is from the coil negative terminal.

Does the 1G motor have coil packs or a dizzy. If it uses coil packs you may be able to use the tacho signal from the computer but I'm not 100% sure if it will work.

and the other 2. ignition, just off the "on" position on the ignition yes?
and crank trigger, take that off the "start" position on the ignition yes?

Yes, and yes .

[love ke70]

the 1g has dizzy. no coilpacks. no ecu.

i thought the negative terminal on the coil was a permanent 12v, or definately a 12v when the ign is in the on position?