Gas runs like poo off a trowel

[MacMan]

I filled the Disco with LPG at a Safeway Discount in the morning yesterday and made it about 300m before it started to cough, fart, splutter and backfire out both holes to the point that it was not driveable. It has been running perfectly on LPG for the 11K we have had it, including the drive to the servo. It was not quite empty when I filled it, taking 69L when it will take 76L when it has stopped running on LPG. I switched to petrol and limped back to the servo - was nearly out of petrol too! ULP ran fine, but as soon as I switched back to LPG the same cacophony started.

So, my thoughts are:

1) It runs fine on ULP so it is not electrical.

2) It when running like poo off a trowel on LPG, it is not a regular misfire - random pops and farts - so it is not electrical.

3) It was running perfectly until I filled it, so it could be the LPG itself. I mentioned to the servo owners that perhaps they shouldn't be selling LPG until they get it checked out, but their only reply was that I could make a complaint if I wanted to and they won't check the system until they get more complaints. Riiiight!!! Won't be buying fuel there again... BUT, since the fuel is under pressure from the tank, there would have to be something seriously wrong with the gas. I can't imagine that anything NOT flammable would dissolve into LPG and stay suspended.

4) There is no easy way to dump the fuel out of the tank without ending up in the burns unit of the Alfred, so I am kinda stuck!

Any ideas?

[abaddonxi]

Years ago when I had an F100 on LPG I had the same problem. Turned out it was the fuel line freezing. Solved it with a jug of water. Or wait a while and it unfreezed itself.

May not be your problem, but easy if it is.

hth

Simon

[rangieman]

yep watch the temp gauge check the water the only reason they freeze is because of lack of coolant [water] sounds possible style_emoticons/<#EMO_DIR#>/sad.gif

[loanrangie]

Air lock in the coolant system will cause those symptons, try again at home and check that the converter is getting nice and hot, if it ices up then you will need to bleed it to get the air out.

[MacMan]

Drove to work this morning and the car ran about 90% until it came to normal operating temperature. Once warm, it started the random miss and backfire again.

Kinda puzzling. Did the same thing when I went to move it as in ran fine when cold. I'll see what it's like tonight on the way home.

So if I understand correctly, the LPG system has some kind of heat exchange fluid circuit?

Cheers, and thanks for the input.

[p38arover]

Originally posted by MacMan
So if I understand correctly, the LPG system has some kind of heat exchange fluid circuit?

Yes, the lines from the heater circuit are plumbed through the converter where the liquified gas is heated and vapourised.

Ron

[discowhite]

i know nothing about gas!

now thats out the way, i did have the same symptoms on a gas forklift.
it turned out to be the mixer, somehow making it run rich then lean??

phil.

[Michael2]

Check that the backfire protection valve. If the rubber flap on the valve is open it will run like that. Also check that none of your aircleaner hoses are loose.

[Rovernaut]

May not be the problem, but LPG has a treacle like substance by- product called "heavy ends", after continual use is brown treacle like stuff clogs converters/ mixer diaphrams.
You may find that your converter has a screw in plug underneath, whith the engine warm you can drain this junk out.
I cleaned mine after 150K on mine and was shocked by what I saw.
Also if there is no hot water entering the converter the gas will freeze and not vaporise causing problems

[BigT]

could also be a loose wire on condenser happened to my brother on his F100 took it to gas place they replaced the mixer to no avail, so cost him $$ he didn't need to spend and only found the loose wire accidently when he bumped it whilst doing something else,it used to back fire and breakdown when you wanted to grunt it. may not be problem but worth a look style_emoticons/<#EMO_DIR#>/smile.gif

[MacMan]

Ok. Findings to date. It doesn't really matter whether the motor is hot or cold, it just doesn't want to run on LPG well. Drove it for 45 mins today, left it idling for about 20 mins too. There were times when it was nearly ok and others when it was terrible. Checked the wires and all seems ok there. The converter is getting nice and warm - tracked the plumbing back an the pipes feel nice and firm once it's running with the thermostat open. Consulted father inlaw and he has an old Holden V8 on LPG and has had to put a new service kit in the converter every 50,000km or so for the last 5 years. Previously it was never giving trouble, but the converters started to foul up with a wax like substance and the rubber components were stuffed. He has spoken to a heap of cabbies and 10 years ago they could do 400,000km with no problem, but now they can't do more than a few months without wax buildup. Sounds like this could be the culprit.

Also worth adding - the Premium I bought from the Safeway place to get me home is **** too! Quite breathless at higher revs, but still pretty smooth.

I am going to pull the converter and have a look.

[Disco300Tdi]

When idling on gas, does it surge in the revs?

It only needs the slightest air leak and it will
run like a one-legged whore.

[MacMan]

Nah, revs sit at usual 800rpm.

Just had the converter off. The treacle like spooge inside was disgusting! There was about a quarter of a cup in there. The diaphragm was ok and still supple, but I couldn't split all of the sections and didn't want to force it. The main objective is to get it to run so I can get rid of the gas in the tank and THEN look at throwing a set of seals and gaskets at the converter. I just got it all back together and it seems to run a little better so far... Going to drive it tonight to see how it goes.

Thanks all for the input, and stay tuned for more!

[MacMan]

Been driving it today and still have poo and trowel problem.

Runs OK on LPG for a while then starts spluttering, swap to ULP and it's fine, swap back to LPG for a bit and it takes a while to sputter again. I have checked the converter and it is too hot to touch all the time so I can't imagine it's freezing. Going to take it for a long drive today and burn off some of the LPG and then I'll take the converter off again later in the week to see how much more **** I'v collected.

All wiring is OK as far as I can trace. Also want to pull the plugs to see what condition they are in. The 4500km of sustained highway running might also have worn them a bit, but I have some new ones to throw at it if they need a clean.

[Ross]

I have a s1 disco that i had gas fitted to in August. mine started with a very similar sounding problem on saturday. mainly it cuts out when you come to a stop or try to pull away, it also sometimes coughs and splutters at 100kph. runs okay on petrol. idle is a bit rough though. i rang the gas converters and they will look at it no problem but of course they aren't open saturdays and close before i can get there from work during the week, so i'll have to ask for time off

[loanrangie]

Ross, sounds like i'm the same sort of problem, mine stalls when the revs drop and its hard to start, runs **** on petrol too so its not limited to the lpg. I will at the dizzy first as i have a feeling that is where the problem is, sometimes i have to crank it over for 10- 20 secs before it will fire up.

[MacMan]

Been trying to run all the gas out. Only another 150km to go... :evil:

It has, however, started to run a little poorly on ULP, which makes me think I am dealing with a spark problem either as the sole cause, or a contributing factor.

Going to try:

- new coil
- new leads
- clean contacts everywhere
- swap back to old rotor and distributor cap
- check air gap

Done some reading, and a number of more reasonable sources suggest that any ignition problem will display more severe symptoms on LPG than with ULP.

Ain't life fun!

[abaddonxi]

Umm, bad earth on non-oem rotor like in this post?

http://www.aulro.com/modules.php?name=Foru...highlight=rotor (http://www.aulro.com/modules.php?name=Forums&file=viewtopic&t=7246&highlight=rotor)

Cheers

Simon

[MacMan]

Hmmm. Might try putting the old rotor and cap back in. The current one came from British4x4 and went in 5000 (6 weeks) ago.

Just put new leads and coil in, same problem straight away. All low tension terminals were cleaned and looked OK.

Back to the shed!

[Michael2]

pull out a spark plug as see what color it is. The color can tell you how the motor is running. It may yield a clue and save on some costs.

Use good quality ignition parts. I replaced the rotor cap on my RR when I bought it 190,000km ago and the only ignition items I've replaced since are spark plugs. Good quality leads sure pay for themselves. A friend with a disco found it ran remarkably better as soon as he replaced the leads.

I hope it all works out well, let us know what you find.

[MacMan]

Problem solved in a not so scientific manner!

I took the dizzy out, reset the airgap to 0.25mm (was about 0.30mm which is still in spec), cleaned the earth terminal on the amplifier and threw in the old Lucas rotor. It now goes perfectly again on LPG and runs as well as it ever has on ULP. So it would appear that it was one of those three. Since the problem was escalating, I doubt it was the airgap - it was as I set it - and the earth terminal was not that dirty. My money is on the "new" rotor, and there is an easy way to test that. I'll drive it as is for a few days to make sure it was not just behaving itself to mess with my head, and then throw the "new" rotor in.

At least she's running again.

BTW, pulled two random plugs yesterday and they looked fine. Some soot on the insulator, but the electrodes were the right colour. That appearance fits the likely ignition problem to a T.

[101RRS]

Originally posted by MacMan
and threw in the old Lucas rotor. It now goes perfectly My money is on the "new" rotor, and there is an easy way to test that.

Was the new rotor a genuine item - the aftermarket ones are crap and fail after about 3 months - have had the problem myself and heard it from others. The genuine item is the only way to go for the rotor.

Gazzz

[p38arover]

Always be careful pulling the rotor an the V8 dizzie. It can be hard to remove and it's easy to damage internals. Some recommend breaking the rotor to remove it ot prevent danage to the dizzie.

Ron

[MacMan]

Rotor was NOT genuine Lucas, and had not even been on for 3 months. Before I blame it officially I have to test the running with the non-genuine part again, but if that's the parts I will be speaking to the British4x4 mob. I did pay $30 odd for it and if it's faulty they should know.

And Ron, I know all about the pitfalls of removing the rotor. I managed to bugger myself and the distributor the first time I removed it. The shaft was bone dry and it was rusted on. The mob servicing it obviously skipped the line where one reads "apply a small amount of engine oil to the distributor shaft".

All good - the beastie goes again, and I have a spare coil and leads now to add to the travelling kit.

[loanrangie]

Hmm, might go and get me a new rotor / cap and see if i can get mine running properly again. Thanks for the update.

[Ross]

Just got my car into the place i got the gas conversion, the problem apparently was the "safety timer" what ever that is. i will be seeing how this now runs for a while. after seeing what you guys are saying about other area, i will be checking them soon.

[MacMan]

FINALLY I got to swap the rotors again to get to the bottom of this. The culprit WAS the non genuine rotor.

I am going to let the suppliers know it was a dud and see how they respond.

Cheers,

Mike

[Steinzy]

Glad to hear you got to the bottom of the issue. I will be keen to see how the suppliers respond :oops: