Sparkplug will not ignite propane

[cebaero]

Hello! I successfully got my spark plug circuit working. I hooked a 12v 9a lawn mower battery up to a dimmer, then ran that through a 15$ ignition coil from amazon, then to a plain old bosch sparkplug. When hooked up and the dimmer is set just right, the sparkplug constantly sparks, almost like a taser. It looks great and thought that it would work just fine, until I tried to get it to light propane. I set everything up as it would be in my flametube and turned the propane and sparkplug on, and nothing happened. I have the sparkplug positioned under the propane so it falls onto the sparkplug. However, it just would not light. It got to the point where I took the sparkplug out of the flametube end cap and tested to see if it would light a lighter. I held a regular cigarette lighter up against the spark and let the fuel out of the lighter, and it would not light. It almost seemed like it would put the spark out every time I opened the gas from the lighter.

Does anyone have any thoughts? Do I need a stronger battery? A performance ignition coil? Anything would help!

P.S. the propane is to go on to ignite kerosene, it is not my main fuel source

[enginewhisperer]

you must be getting an extremely weak spark.

Try just tapping the wires from the coil on the battery terminal briefly and see if it makes a more solid spark at the spark plug.
The spark should make an audible crack sound.

[racket]

Pure propane won't burn , it needs to be mixed with air first to provide a combustible mix , so positioning is important.

You don't need a performance coil .

Try using an automotive "flasher/blinker" unit and a relay to replicate a set of ignition points , your "dimmer??" unit might be the problem

[richardm]

What kind of dimmer are you using Most dimmer I know of work on AC current. You could get a cheap high voltage generator doing the job from the battery no coil needed

[cebaero]

Aug 12, 2024 16:47:02 GMT -5 enginewhisperer said:

you must be getting an extremely weak spark.

Try just tapping the wires from the coil on the battery terminal briefly and see if it makes a more solid spark at the spark plug.
The spark should make an audible crack sound.

I mean I can hear the sparks with my current set up. Im thinking that maybe the dimmer is producing sparks at such a fast rate that they are weaker. I might need a switch that slows the frequencys of sparks down. 

[cebaero]

Aug 13, 2024 4:42:29 GMT -5 richardm said:

What kind of dimmer are you using Most dimmer I know of work on AC current. You could get a cheap high voltage generator doing the job from the battery no coil needed

This is a DC dimmer off amazon. Ill look into those, thanks

[cebaero]

Aug 12, 2024 16:50:02 GMT -5 racket said:

Pure propane won't burn , it needs to be mixed with air first to provide a combustible mix , so positioning is important.

You don't need a performance coil .

Try using an automotive "flasher/blinker" unit and a relay to replicate a set of ignition points , your "dimmer??" unit might be the problem

All my tests were done in open air so I couldnt see it being that problem, I just positioned my FT end cap into the FT to simulate actual running conditions as best as I could, without having the turbine outlet end welded up yet so air could get through there. Im now almost thinking that my dimmer is maybe just sparking the plug so fast that its not having enough time to charge up thus giving a weaker spark. Currently looking into the flasher blinker unit. Would I need a relay at that point or could I just hook something up like the product in the link before the ignition coil and maybe an on/off switch?


www.amazon.com/4-5-30V-10Amp-Blinking-Flasher-Module/dp/B095LDN44H/ref=asc_df_B095LDN44H/?tag=hyprod-20&linkCode=df0&hvadid=692875362841&hvpos=&hvnetw=g&hvrand=9470320599552034590&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9015297&hvtargid=pla-2281435178778&psc=1&mcid=7377bbd9ab7630ab864e427a1d38fc6f&hvocijid=9470320599552034590-B095LDN44H-&hvexpln=73&gad_source=1

[noshell]

I had this problem. You do need a good strong spark, I also found with my setup making the gap much larger helped tremendously. A BBQ ignitor never works for me. I usually run an engine (like a strimmer or something) and run my turbojet spark plug in series with the lawnmower spark plug.

if I had to purchase something I would look into those high voltage generator things from aliexpress or ebay.

[noshell]

Im planning on using a glow plug exclusively on my next full build (liquid fuel), my logic is that they can start up a diesel heater it should start up a turbojet.

[cebaero]

Aug 12, 2024 16:47:02 GMT -5 enginewhisperer said:

you must be getting an extremely weak spark.

Try just tapping the wires from the coil on the battery terminal briefly and see if it makes a more solid spark at the spark plug.
The spark should make an audible crack sound.

When I tap the wires onto the battery terminal, the spark is strong enough to light fuel. But I just cant get my sparkplug to do the same. I even tried to replace the dimmer with an on/off switch to see if it would spark but it would not spark enough to light fuel.


www.amazon.com/Bosch-Automotive-Double-Iridium-Spark/dp/B00515NJTI/ref=asc_df_B00515NJTI/?tag=hyprod-20&linkCode=df0&hvadid=693571309629&hvpos=&hvnetw=g&hvrand=2176933866686122573&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9015298&hvtargid=pla-647212352117&psc=1&mcid=4e1290fdc40531e2a8eba230d231f3a5

Is there something wrong with this sparkplug? I have tried so many things and nothing will work. I thought this would be the easiest part lol but I have been stuck on this ignition system longer than any other part of this project. I am looking into switching to a glowplug, does anyone have any advice on those? Or would anyone be willing to share their ignition system that worked out? Im just at such a loss and anything would be very appreciated.

[richardm]

Check Andy Morris ignition system . You dont really need the spark gap tube ( Old devices hard to get today) The spark plug gap will play the same role
I m sure Mr Morris would be glad to help so Im going ahead and giving you a link to one of his ignition video

www.youtube.com/watch?v=bU-bUAiL4Xc

[racket]

Hi
I used a car coil in conjunction with a flasher unit and a relay , positive from battery to flasher and coil , the flasher operates the relay to ground out the coil .

[slittlewing]

You should be easily able to ignite propane with a spark generator and normal plug. I can ignite 80% diesel and 20% petrol with the same setup (and no spark gap).

www.aliexpress.com/item/1005005972757262.html?spm=a2g0o.order_list.order_list_main.23.58dd1802Q2Apin

You need to make sure you are using a copper core spark plug, copper core HT lead and boot (no resistor in plug or boot, no EMI resistive type HT lead)

Your spark plug also needs to be in the right position

BR

Scott

[richardm]

If you do have a spark then stop working on your igniter. the fault is somewhere else. Think of a BBQ or a propane torch igniter. Only a tiny spark from a piezo igniter does the job.
It is more likely a problem about propane / air mixture and or placement of the spark plug in relation to the nozzle.