Thread: 99 RR LPG system not working

Whilst a mixer system is not recommended for the Thor engine owing to the likelihood of backfires, it should perform OK, especially as it sounds like it has stepper motor control of the gas.

If the system has fault logging, then the first thing to do is to get the logged faults read. You may have a faulty pressure sensor (for starters) which is causing the gas to be shut off.

The backfire may have damaged the MAF sensor. Fortunately for you, your car has the less expensive one (cf. the GEMS engine). However, you say it runs perfectly on petrol so that may rule out a faulty MAF sensor.

The engine then ran more smoothly however would drop out occasionally like it was starved for gas.

couldn't be something simple like a bung connection to one of the solenoids on the convertor/stop valve/tank valve could it ? intermittency followed by total failure could point that way.
alternatively, if your sprintgas box features them, there might be a couple of tiny trimmer pots next to the multiplug. on mine one of these dictates when the changeover occurs and it is very sensitive. from memory, if turned completely one way it would, as you say, cause the gas led to flash but yet not permit the switchover in fuels to take place. what numbers are on your sprintgas box ?

Hi guys, thanks for your help. I'll check the numbers on the sprint box. Also, as far as I can tell, the MAF seems ok. I had it off and gave it a clean with some spray on elec cleaner, however the box thing that mounts off the air tunnel behind it is broken, and has been taped up. Not sure what this part does?

Originally Posted by senrta

Hi guys, thanks for your help. I'll check the numbers on the sprint box. Also, as far as I can tell, the MAF seems ok. I had it off and gave it a clean with some spray on elec cleaner, however the box thing that mounts off the air tunnel behind it is broken, and has been taped up. Not sure what this part does?

I think that is an induction noise silencer.

Originally Posted by p38arover

I think that is an induction noise silencer.

hmm, that would mean apart from noise I don't really require it so I could remove it altogether? there seems however to be two of them then, it is the first one after the maf that has a huge hole in it, taped up with electrical tape,

Hmm.. Maybe you'd better post a pic of exactly what you are looking at.

first one after the maf that has a huge hole in it, taped up with electrical tape,

when you say 'after' the maf is that as in between the maf and the plenum chamber intake ? is the tape bound around it or is it arranged as if to be a sacrificial weak spot ? some of the backfire valves i saw on the web once looked like a tupperware tub lid clipped over a hole in the trunking designed to yield to the sudden increase in pressure caused by the gas in the inlet manifold backfiring, thereby reducing possible damage to the maf and/or airbox.

i still don't see that any of these problems necessarily relate to the loss of the ability to run on gas. can you 'force' gas mode from the switch (yellow light ON) if so do all three solenoids click when you switch on ignition?

when i recently took my gas conversion for certification the only mod the fitter insisted on was to fit an extra in-line fuse in the engine compartment solely to isolate the tank valve. this is in addition to the fuse on the gas control system. if this fuse exists on yours, and was blown or badly connected it would allow the system to appear to be functioning properly including hearing clicks from the other two solenoids but as no gas would flow from the tank it wouldn't go .

i've just remembered that there is a dodgy tank valve recall. i think its for a 'sirtek' brand or similar. i don't know whether they could 'fail' closed but i know they can fail open on the fill valve. there was one that did just that the other day in ocean grove. might be worth a brand/number check on yours.
i think i saw the recall on the government lpgaustralia website but seeing as that organisation and i are at war atm i'm not recommending anything on their site as remotely relating to the truth anymore.