LPG issue

[Skexis]

My recently purchased dual fuel NP 3.5 has an issue when running on gas. Difficult to describe but it feels pretty much like a learner driver stalling a car. Has that same cough and lurch. It will do it several times but it will keep going and seems to do it only when the accelerator pedal is being depressed as if I lift off slightly it stops doing it. Car runs fine on petrol. The gas tank was empty when I picked the vehicle up and filling it was the first thing I did at a BP servo. Just wondering if it might be bad lpg so I'm thinking of emptying the tank and trying again at my regular servo as I don't want to take it back to the dealer if it's something as basic as that. Question is, how do I empty the tank? Can I just loosen a hose somewhere well ventilated

[erad]

I think to just let the gas go is really dangerous. Even out in the bush somewhere, a random spark and it would be a big flash. LPG is heavier than air and even though you say 'well ventilated', it is still ultra dangerous. It would fill a low area. I don't know of any way to dump the gas safely.

I got a crook batch of gas in Bathurst once whilst towing my caravan. The car would run OK on light throttle, but backfire badly underload. I was travelling, so I used petrol to go uphills, and onceon the flat or downhills, I switched to gas. After 200 km or so, I refilled with gas (diluting the crap I had in the tank) and it seemed to sort itself out.

[Skexis]

Ok so I took it out for a decent run today and have worked out the lurching problem only happens when on LPG and I'm accelerating anything more than very light pressure on the pedal. Seems worse after switching to LPG after running on petrol.

Noticed also that on one occasion whilst coming down a reasonably steep hlll all the green super select lights went out and the orange centre diff light started flashing. No idea why.

[erad]

You say "Recently purchased NP 3.5". Is this the first time it has done this to you on gas? You are blaming the gas, but crook gas is unlikely - I only had a bad batch once (from United in Bathurst), but over the years I bought thousands of litres of gas for a variety of vehicles with no problems at all.

More likely, there is a problem in your gas system. You may be running too lean on gas. The best way to resolve this is to go to a good (if you can find one) gas man and get it checked out. These engines are very sensitive to tuning problems on gas. Once set up they are brilliant. The High Tension leads and spark plugs are critical. Even teh spark plug gap is critical. Champion recommended that the gap be closed by 0.1 - 0.2 mm over the recommended gap for petrol running. That is a good move because it reduces the strain on the HT leads.

[George Whiley]

It may be worth trying an "ECU relearn" which resets the ECU so it can adapt to being run on gas again

[J B]

You may have a clogged injector. I had an NM on gas that used to get blocked injectors. I got rid of it in the end.


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[Skexis]

I agree it's most likely the gas system itself. I bought it from a dealer so they can fix it under the three month rule. Noticed today the front nearside sidelight doesn't work either and it's not the globe.

[erad]

If you have a warranty, get it done ASAP. the used car warranties typically are not worth the paper they are written on, so you may have a bit of a fight on your hands, but start off politely and hopefully they may fix it for you.

[Skexis]

Photo heavy post

Update: following on from a question from a forum member I went and had a closer look at the LPG system. Firstly there is no evidence the tank has been tested at it's 10 year mark and 2, it appears the LPG plate in the engine bay has been clumsily altered to make it appear the installation is less than 10 years old. The supplied paperwork clearly indicates the unit was installed in 06. So, do I simply let the dealer fix the issue and retest the tank or is this something that should be taken further given it could be construed as fraud?

[Chainsaw]

Photos = Evidence From what you have shown here, the dealer (and Gas Examiner) have a lot of explaining to do IMO. In Qld the vehicle has to have a current RWC AND if fitted with LPG has to have a Gas Certificate as well, to change the registration to you.

Here is a link I have found who just happens to be in SA. http://www.advancedcylinder.com.au/i...tpage&Itemid=1
they will be able to give you a lot more info re this.

Now with a sytem 10 years old I would be looking at replacing the converter (that's the round thingy in the engine compartment) not only the diaphram's get hard and not as responsive, but biggest problems would be corrosion in the internal galleries. I have found IMPCO system best and most reliable. Even if you have to pay a bit to replace the Converter with IMPCO put on a IMPCO Mixer as well.

Also when you do sort it out, always ensure you have at least 1/4 tank of petrol and use it now and again.

Rod

[erad]

Try getting the dealer to fix the running problems with the gas system and also the out of date gas cylinder. If that fails, there are plenty of places who do cylinder retests. I had to remove the cylinders from both my vehicles and take them to the teest centre, but if you don't feel confident to do that, take it to a gas mechanic and get them to do it all for you. First - try the dealer who sold you the car and point out to them that the car strictly was not roadworthy when sold and that it runs like sh1t on gas. If you have a warranty they should fix both, although I think you may fall short on the warranty because of the car's age.

Regarding the 1/4 tank of petrol, agree with that statement. When running on gas, the electric petrol pump in the tank still runs. The petrol cools the motor - yes it is OK because there is no oxygen there to go bang. If you get too low, the pump can get stuffed. On my NL, I fitted a normally closed relay to the petrol pump feed line. When the gas system was activated, the 12V signal triggered teh relay and opened the contacts, isolating the petrol pump so it didn't run. This meant that I could run the petrol tank dry when I was outback and within range of a refill. I kept the gas tank full and used petrol, refilling as necessary with a jerry can. Using this system I have done a trip around the block twice and each time used only 2 tankfuls of petrol. It is a simple job to install the relay.

[Skexis]

Decided to book the vehicle in for an RAA check as well in case there's anything else I've missed that the dealer can fix whilst he's at it.

[Skexis]

,,,and the RAA check revealed nothing more than minor insignificant items, none of which are an issue. Dealer currently has the car back and is having the tank tested so looks like I'm all good.