99 RR LPG system not working

[senrta]

Hi guys,
I'm hoping that you may be able to help me or point me in the right direction as I'm now getting the run-around. I'm fairly knowledgeable on gas as I've had a fitted to a few old Holden commodores in the past.

The car is a 99 Range Rover 4.0l with 200,000k's on the clock. It has been serviced religiously, with all details recorded every 10-20,000k's. The engine compression seems stable and there is only mild tappet noise. At some stage before buying, the engine has backfired as the airbox and airbox tunnel line show damage.
The LPG system was installed by _ _ _GAS in November 2007. It is a sprint gas mixer system with a large donut tank. The unit is apparently a 2 stage learning unit.
When I bought the car, I was told the system was working, which it did, for a little while. I found the car idled pretty rough on gas, so went and saw a mechanic friend who put me onto some better 8mm ignition leads, to help better ignite the gas. The original leads were 7mm Belden variety, I changed the leads to NGK. The engine then ran more smoothly however would drop out occasionally like it was starved for gas. The indicator light on the LPG level gauge started flashing soon after and now I cannot switch to the LPG system, the car only running on fuel. Any ideas?

The car runs perfectly on petrol but now not at all on gas!! Any help or ideas would be great. As fas as I know _ _ _GAS have a 3yr warranty, but I know I'll have problems due to buying the car afterwards.

Thanks for your time,
Ren

[p38arover]

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.

[pomonastik]

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 ?

[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?

[p38arover]

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.

[senrta]

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,

[p38arover]

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

[pomonastik]

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 .

[pomonastik]

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.

[senrta]

This is a pic of the area I'm talking about. Behind the elec tape is a rather big hole.
The airbox has a hole in the bottom front, but I've reinforced it with some strapping. The replacement price of 300 is a bit rich when it may happen again. I've been told it won't affect the operation.


https://www.aulro.com/afvb/images/imported/2008/11/714.jpg

[senrta]

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? .

I changed the leads to bigger NGK items, changed the coolant, went for a drive on gas and petrol, all okay. The following day, started on gas, went for around 40 min drive, about 5 or 6 times, car power dropped out and nearly stalled when on gas. Stopped put onto petrol. After that, the yellow light on the gas gauge flashes, with the engine light on the dash illuminated. I've tried to switch either way, but it stays on petrol.

I've contacted an LPG fitter who said it could be the tacho wire from the gas computer or the solenoid on the vapour line. They weren't sure about the filling problems. I'm not too keen on going back to the fitter as I've been stuffed around already.

I'll have to get someone to take a listen when i turn the ignition on for the solenoids, as the abs/compressor makes a bit of noise on start. Where do I look for the tank valve, it's a donut tank, I take it underneath?

[pomonastik]

"changed the coolant,"
&
"nearly stalled when on gas"

could it be an airlock in the gas vapouriser part of the cooling circuit ? to test this theory run on petrol enough to open thermostat and have full flow for a while, then feel input/output water lines from the unit. on my classic using an OMVL unit the hoses and the vapouriser would both be HOT to the touch by then, proving adequate water flow.
i'm not sure of the correct air purging method for your model but someone on here will know.
jeez it would be a cheap fix if that was it.......

sorry, don't know much about doughnut tanks. when you find it investigate the manual stop-tap that's probably there too. a very useful thing to know of you ever have any form of fire, even if only to tell the firee where it is 'cos its the first question he/she is going to ask you !

[p38arover]

The valve could be in the centre of the tank (in the doughnut hole). Remove the cover (if it has one) and look in there.

Mine is in there.

There will be another solenoid near or on the converter under the bonnet.

[p38arover]

sorry, don't know much about doughnut tanks. when you find it investigate the manual stop-tap that's probably there too. a very useful thing to know of you ever have any form of fire, even if only to tell the firee where it is 'cos its the first question he/she is going to ask you !

If mine catches fire, I won't be opening the wheel well and removing the screwed down cover over the valve to shut it off. The car can burn! I'm not gunna be incinerated.

[pomonastik]

If mine catches fire, I won't be opening the wheel well and removing the screwed down cover over the valve to shut it off. The car can burn! I'm not gunna be incinerated.

ron, i don't want to be alarmist BUT
its not unknown for a car's occupant/s to be trapped in the vehicle after a collision has occurred. the ambos and road rescue folks want to know two things from the firies before they go to work, is gas turned off and is the battery disconnected ? the only way we can guarantee this to them is if we've turned off the gas valve and physically disconnected the battery terminal. in theory of course if the battery is disconnected then the gas solenoids are shut too but as it's not unknown for airbags to detonate after we've cut the juice so we like to make sure on the gas side too.
i think i'm also right in believing that the only way to isolate the fill line is via the valve. i may be wrong but seeing as fill lines are often within the impact damage area they can be damaged too.

back on thread i have 3 solenoids on my system, one on the tank, one on the vapouriser and theres another on the stop valve with the filter in on the inner guard.

[senrta]

could it be an airlock in the gas vapouriser part of the cooling circuit ? to test this theory run on petrol enough to open thermostat and have full flow for a while, then feel input/output water lines from the unit. on my classic using an OMVL unit the hoses and the vapouriser would both be HOT to the touch by then, proving adequate water flow.
i'm not sure of the correct air purging method for your model but someone on here will know.
jeez it would be a cheap fix if that was it.......

sorry, don't know much about doughnut tanks. when you find it investigate the manual stop-tap that's probably there too. a very useful thing to know of you ever have any form of fire, even if only to tell the firee where it is 'cos its the first question he/she is going to ask you !

yes, it could possibly be an airlock though the hoses do feel hot. I'll have a look at the tank. I was going to add a fire extinguisher to the car, but due to the explosive nature of gas, I'd be out of there too in an incident!

[senrta]

The valve could be in the centre of the tank (in the doughnut hole). Remove the cover (if it has one) and look in there.

Mine is in there.

There will be another solenoid near or on the converter under the bonnet.

I don't think the tank has a cover as it is the biggest round donut available to fit the spare wheel well. My system seems to have 3 solenoids also, I'm going to get some help to see if all 3 click when powered.