LPG Misfire

Post by **coolrunnings** » 29 Jun 2006, 20:11

Just a bit of info, many thanks to Pete for the conversion this weekend. All running fine now.
Set up originally and ran fine on test drive after commissioning.

soon as i got back into town, the engine was lumpy and hesitant and would frequently backfire.

Dumped the multi point spark plugs for single point plugs and all was well.

Can still be a bit of a problem to start first thing in the morning, don't know if anyone has any ideas about this ??

Post by **Flibbertigibbet** » 29 Jun 2006, 20:42

I am no lpg guru but mine has been running on gas for 2 years now.....when starting up I turn ignition switch once until I hear the click of the gas....then turn ignition key back then on again then press down on pedal and it works everytime

Post by **coolrunnings** » 29 Jun 2006, 21:01

already do that a couple of times under advice from pete.

But it won't quite catch first thing, the engine is firing whilst the starter is turning but not quite enough to allow me to stop the starter.

Post by **kevtherev** » 29 Jun 2006, 22:03

Half throttle and .........crank

Post by **speleobod** » 02 Jul 2006, 15:29

Having some mis-firing on LPG. Thought my carbs may need a refit.

What are 'single point plugs' please??

Post by **coolrunnings** » 03 Jul 2006, 12:00

take your plugs out and see how many electrodes you have. 'Normal' type 25 engines will have plugs fitted which have 3 or 4 electrodes.

go to your local halfords or other motor factor and get bosch plugs with only 1 electrode.

Post by **speleobod** » 03 Jul 2006, 18:31

Thanks. we'll try that before an expensive carb refit.

Post by **Mocki** » 03 Jul 2006, 21:35

i have always found full throttle whilst cranking when cold makes for a faster start up on lpg...........

Post by **ghost123uk** » 05 Jul 2006, 11:29

speleobod wrote:Having some mis-firing on LPG. Thought my carbs may need a refit.

What are 'single point plugs' please??

Do remember your carb is doing very little when running on LPG, just the throttle butterfly doing it's stuff, nowt else on it is doing owt.

Post by **pastyman** » 10 Aug 2006, 14:41

Hey, Coolrunnings when your engine was running lumpy and back firing was that on LPG or petrol?

I'm wondering if it could be a timing issue too. LPG is higher octane than standard unleaded, so you can to advance your engine to get more power/efficiency from the LPG. I have mine advanced, but this is harder on the starter motor which can make it harder to start. Especially if you start on petrol, where you start to run the risk of pre-ignition and backfiring. - Could be that Pete advanced the timing a bit for you? If it was already a bit advanced could be that you are now too advanced to run comfortably on Petrol?

I like to advance the engine by about 5 degrees and start on LPG. I expect to get through starter motors a bit quicker than expected however.... ideally I would get a thingumy to change the timing.... Steve, do you sell them? If so I might be interested!