The V8 Owners Forum -

Hi, I bought an 81 reg RR which has the 3.9 and 5-speed box fitted along with an Emmegas LPG system. This was sold as a non-runner but after a couple of days trying various "fixes" i finally got it running albeit a little roughly (been lying in a garage for a long time). I replaced plugs, points, dizzy cap and rotor arm, also a new set of 8mm leads so everything basically on the ignition side is new so i dont foresee any problems with that lot. I'll get it tuned later but the problems i have now with my V8 3.9 ignition setup are the following.

Feeding +12v to the coil. There is an Emmegas LPG system fitted and the wiring is obviously modfied to suit so lots of extra non RR wires all over the place making the manual wiring diagram difficult to follow.

The +12v feed i can see goes through the LPG box (small plastic home made container that has the LPG relays & switching in it) then leaves the box, along with another wire and goes to the ballast resistor. Opposite end of the ballast resistor the wire goes straight to the coil +12v terminal.
It was my impression there was a +12v feed from the starter to give the extra voltage kick when starting the engine? if so, why only 1 wire on the coil +12v?

To get it started i eventually just did a basic wiring job, running a wire straight from the battery to the +12v on the coil and the engine fired up and ran. Problem now with me bypassing the ignition switch is i have to disconnect the +12v feed to the coil to stop the engine as it won't shut off with the key. I reckon the ignition cutoff will be in the LPG wiring "box" but i have neither the schematics nor wiring manual to have a look. Anyone have a similar system fitted that can provide a wiring diagram ?

The LPG switch on the dash has 3 positions, I - O - II and is marked B (under the I) & G (under the II) which i presume refer to benzine and gas. The engine fires up on the I position but not O or II. I have no idea if this is setup to start on petrol and switch over when warm or start straight on gas. Any ideas on how i can tell?

So basically any help or further info would be great and appreciated, i so want to get this beast on the road )

cheers
Scott

All the LPG systems I have ever seen do not affect the ignition system at all? The changeover and cutout just work on the fuel side. There is a feed from the ignition into the LPG system however so it knows if the engine is running / stalled so can shut off the gas accordingly.

But I don't know anything about the EMMEGAS system.

Chris.

Hello Scott,

Ignoring the fact that the LPG system clearly has some form of home brew interruption to the ignition process, but that you did jury-rig the ignition system to run direct from the battery but cant be switched off, isnt it possible just to emulate a regular ignition system where the ignition switch controls the mode. Cranking, Running, Off, etc

References to electronic ignition removed - apologies for misleading you.

Once you get the ignition working in a conventional form and the "beast is on the road", you can then sort out the other interrupting connectiions later.

Tracing wiring is not that difficult, follow the wires, note the colours, draw the components and the connections, scan the image and post the result on the forum for interprettation.

The above suggestion only gets the ignition running ok, and does not address your Ballast Resistor issue but that is a simple well documented cranking/starting process that could be separately addressed, not being part of the ignition system, as it were.

Let me know if i'm way off the mark here.

Thanks for the replies Chris & Ramon, i'll be working on it tomorrow so i'll take pictures before i start to show you what im up against then again when im done. It may help someone else too so there may be a bonus there somewhere. There are wires coming out everywhere on the engine loom, many are dead ends, some taped up and some just lying there bare.
I dont know how much of a difference there is between the EFI ignition and the standard points/condenser system i have with regards to sensors/amplifiers etc but i think maybe the best way to go about it is to just lay some fresh wiring as per the manual diagram.
I've already had a chat with the LPG garage and the bloke said he would check it all over then completely rewire the system so that hes happy that its safely wired (i cant blame him tbh, as you'll see with the pics hehe)
Anyway, off to bed to get some decent rest.....long day tomorrow

cheers
Scott

I've just finished trouble shooting the ignition system on my 101, which should be very similar to the system that you have, so here goes!

The ballast resistor is important - it stops you from destroying the coil.

For starting the vehicle, you should have a 12V feed to the coil directly from the starter motor. However, if the starter motor has been replaced at some time, it may not have provision for this feed. In this case, tap into the ignition feed to the solenoid.

The ballast resistor should have a 12V feed from the ignition when the engine is running, giving 6V at the coil. Without the 12V from the starter motor, this is unlikely to be enough to start the vehicle, but once started, the vehicle should keep running with no problems.

Also to note that the ignition system is independent of the fuel system with both carbs & EFi.

Chris.

jockamok wrote:I dont know how much of a difference there is between the EFI ignition and the standard points/condenser system i have with regards to sensors/amplifiers etc

Scott, Sorry about that, Ignore the Efi references on my post, I completely missed the fact it was a points system.

The only valid suggestion is to rewire the connections thro the ign sw protem until the rest can be sorted out as suggested.

Apologies

Ramon