lpg problems

hi i have a problem with my rr lpg it runs on petrol fine but when swiched to gas it swichers back to petrol when reved hight but goes back to gas as the revs are dying please help

what sort of gas system do you have on what car?

single feed landi les98 rr 3.9 v8 cheers daz

how do you know it cuts to petrol and back to gas?
has it always done this? if not then are there any loose connections in the engine bay that might be coming adrift with the vibrations at higher revs.. other than that there could be a problem with the valves in the tanks.. if it's an old install ( only assuming that as it is single point) then these valves only last about 3-4 years max apparently (mine are 5 years old and temperamental to say the least)

It's quite a common fault. I've been told it's to do with the drop in pressure which makes the system think that the gas has run out. When the pressure is restored and the engine senses it's warm enough to run on gas again then it reinstates the gas.

I'm no eggspurt on lpg systems so it could be that the guy who told me was talking out his arse. It did seem like a reasonable explanation to me though.

yeah I have also heard that Ratty but I've not heard of single point installs with low pressure cut offs....

mjltigger said:

yeah I have also heard that Ratty but I've not heard of single point installs with low pressure cut offs....

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Yeah I know what you mean. I'm wondering if it has summit to do with voltage change between the engine being reved and dropping back to tickover.

it sounds like the rpm signal has been taken from the injector wires, a common error. when the lpg system sees the car is on over run it thinks the engine has stalled, reverts to petrol, finds revs then back to gas.

i think it should go onto a blue wire in the loom but i'm not sure on this!!! the system should also have an over run function to cut gas when coasting to tickover.

this is what i have read and hopefully its the case(and correct)

it sounds like preasure its like its not getting enough gas it was working fine untill then is it just a case ov puttin more gas in but my swich says its full i have 2 tanks could one tank be emty???????
cheers daz

daz0000 said:

it sounds like preasure its like its not getting enough gas it was working fine untill then is it just a case ov puttin more gas in but my swich says its full i have 2 tanks could one tank be emty???????
cheers daz

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The same source as my previous post also said that LPG systems draw equal quantaties of fuel from each tank at the same time rather than emptying just one tank at a time like you would if you had multiple petrol tanks.

If this is the case, it is possible that either one of the tanks is empty or the regulator on the tank could be faulty.

if your tanks are a few years old the valves may be fubar in which case there's a good chance one tank is full and the other is empty.. that happened on mine.. give them a bang and see if they sould hollow or full.. if one is full and the other empty then you have a valve issue - may be hardware or electrical.. on mine (although the symptoms were different) it was electrical.. the numpty that fitted the system used the eggsauce to hold the lpg loom off the floor and I had to get the whole thing re-wired..

i think one could be emty because if u tap it it sounds hollow and the other one doesnt cud that be the problem and would it meen a faulty regulater could i test? cheers daz

if one is empty and oine is full then you have a faulty valve (dunno if that's the same as the regulator) on the full tank.. and by the sounds of it your fuel guage is in the full one hence your full all the time reading..

I'm not sure that would cause the other symptoms you describe but if you find sommat wrong then fix it and see what happens.. the one full one empty scenario is likely to cause underfueling and misfires.. did on mine anyway..

whether it can be done at home.. no idea.. two issues I can think of.. one is getting the gas out of the full tank and the other is making sure the new part is fitted gas tight.. but I am sure there's someone on here that can assist or advise

i believe you can replace the valves but its probably easier and cheaper to replace the tank. to test the valve(or at least the guages, hopefully both are working) you could measure the resistance at both guages, one will have wires on, one wont but this is where you need to test.

make sure the tanks are set with the valve part about 30 deg from top centre. if one is not emptying then as a temp measure you could turn it off, this will make it safe. it could just be the solenoid on the tank, if there is one for each tank, compare resistance on them. once you have found the faulty tank and isolated it, you can remove it and put in another tank, use a compression fitting prolly 6mm to join the pipe and a new piece of pipe to make up the section. or the best method would be to empty the good tank or turn it off. undo the t's and re pipe from there. depends on ease and accesibility but the less joints = less leaks possible.

been out in the truck all day runs on gas untill above 2000rpm once above swichers to petrol and back to gas when it comes back down to 2000rpm thinking ov getting the leeds and software of ebay

i have the leads and software mate if you want to pop over or i'll pop over to you. the leads arnt expensive, its just waiting for em that does my tits in!! you can download the software for yours at: ELPEGE | LPG | lpg-software, návody na lpg zaøízení, schéma just click on aeb then on leonardo, it'll download a .exe file(aplication file) its safe and no viruses, i have it on mine.

there are other progs on that site too, the site is polish but the software is english!!

let me know if ya wanna pop over, you have my mobile number, i'll be going swimming i think today at some point this aft but any time before or after is fine!

could pop over for avbout 12.00 if thats ok

been looking for the software mate and i cant seem to find the correct version, will keep trying. let me know when you get hold of cable and soft. i'll be interest to see what the problem is!!!

ive found the software and it works the software that is im going to order the cable

is they any way i could put the software on hear?