LPG Problem

[zien49]

Hi All
LPG Loss of power. Mk1 V4 2Lt Auto Box LPG

Can any one help, we where coming along the M62 today running on LPG, and the power just started to drop off it went down to 20 MPH I limped onto the Pontefract junction had a look and a think then changed onto petrol it revved up ok so I drove on to the A roads then stopped and changed back onto LPG it revved up ok but would not drive above 20 MPH so came the rest of the way home on petrol when we got home rain stopped play so will have look tomorrow. I have just got the LPG fitted and did the same run last week as a road test with no problems. Has it’s the first problem, as one any ideas?. (I put sum more LPG in and tested but it was the same)[Thanks to the chap that offered to tow us of the M62 if you use this forum].DEREK

[24vMk2]

Has it backfired on LPG?

May have moved the mixer on the top of the carb.

Mine does it, if it has backfired.

[Petrolhead41]

i had a Jaguar XJ 40 with Lpg fitted which backfired and kept burning out the fuel mixture sensor wire ( at £75.00 for a second hand replacement ). i was told that setting up the LPg so it doesn't back fire isn't easy.

Sounds like your LPG ain't getting through in enough quantity when engine is under load, may be that a backfire has affected it.

As you just had it fitted i would suggest taking it back and asking them to look at it.

If it's a home fitted kit i would suggest finding a company that fits LPG and ask them.

If it's not getting through and its going somewhere else l would make sure you have a large full fire extinguisher with you, you're gonna need it.

You can't take a vehicle which has Lpg fitted on the channel tunnel train, it's good when its ok but can be frustrating.

BUT, bear with it as it's one hell of a cost saving on fuel.

[zien49]

Hi Petrol Head
I was thinking along the same lines. Do you tkink it's posible to fit a one way valve?. DEREK

[Petrolhead41]

On the Jaguar there was the option of fitting a back fire valve which would have protected the wire for the fuel sensor, but as the car was always on LPG l just disconnected the plug to the sensor and it ran on a pre determined setting.

There should be some kind of valve which will do that, the backfire happens on over run when the engine doesn't need the gas and it goes into the inlet pipe. Which then ignites inside the inlet pipe causing the problem, it's nothing to do with a normal type of back fire.

Main thing is to check the fittings, l am sure that insurance compaies specify a certificate of some sort for insurance purposes. If you have one then take it back to where this was issued, if not then you will need to find a garage which fits ( and understands Lpg ) and get a certificate from them.

Without a certificate if anything happens l doubt if you would get paid out from your insurance company.

[zien49]

Hi Petrolhead

I have spoken with Autogas 2000 in Thirsk today and they suggested the diaphragm is split. If you blow down the feed pipe and if you can keep on blowing the diaphragm is slit, I couldn’t keep on blowing. So am going to fit my other vaporiser/diaphragm in the morning, (I don’t know if it’s any good) and there is a one way valve you can fit so I think I will fit one? DEREK

[zien49]

I fitted the other vaporiser/diaphragm and played with it for along time and still can not get it to run ok on gas, I will try at the weekend.

[cad69]

Okidoke, I run on lpg 99% of the time until it runs out and switch to petrol to get to a gas station. Initially I had 2 problem. One: air leak between carby and intake manifold. I could rock the carby around and notice different idle speeds, it took only a very minor air leak (ie air getting sucked in) to cause a major problem. Also if it backfired it could damage seals causing the above. I also was running an earlier style lpg air filter which wasn't squarely supported on carby causing nuts to work loose on carby. Second: Lpg needs a much healthier spark than petrol to run well, tho from what you mention it doesn't sound like spark but as a matter of course we need to be much more diligant with plugs, leads and points. another aspect that you need to check is that the gas is being heated enough so as not to be freezing in the pipes. The heater hoses are generally used to heat the gas. If your thermostat has been removed or not closing properly your coolant may not be hot enough to stop gas freezing. Try pouring hot water over your pipework (could crack something so be wary) and see if it runs better for a short while. If you have your heater on try running with it off so more heat goes to the lines. I disconnected my heater altogether but then it doesn't get real cold down under. Cheers Hugo

[zien49]

Hi All the LPG Men
Well the weekends been and the LPG is still not running right. Rechecked all the system again, and all I could do was get it to rev, up with my hand over the venturi for the gas supply but as soon has you removed your hand it stopped revering. So I made a cap to go over the venturi with a set of holes in it so it would tick over made from a spray paint can top then I added holes until it would rev, up, then tried to drive it didn’t work and it didn’t drive on petrol as well. So in the morning it’s going to LPG MAN if that doesn’t work EBAY. (CAD69 thanks for your input) DEREK

[madmark]

it sound like you are getting to much air! years ago i had a escort van that wouldnt run on gas unless you had the choke out!

[zien49]

Hi Madmark
I will try that on the way to the LPG MAN. (What I don’t under stand is it ran ok for 150 or so miles before it fell off song.) DEREK

[madmark]

lpg is great when its going but a pain when its not ,lets hope it something simple!

[zien49]

Hi All LPG MEN
Well it went to the LPG man and he had a look and found a blocked pipe but gas was still getting thru and pressure was building up, we removed the pipe and fitted a new one and it did run a little better. So we tried to drive home but it was no good, stalling, cutting out, not revving, and not pulling on flat & and up hills. I put it on to petrol and it did not run too good on that (I will check & set it back up). The only good that came out of the trip was I called at the scrap yard and found a K & N air filter which I fitted & made sum adjustments. On road test I stopped and adjusted things but it still did not run ok. So it is now in the garage and it’s had a good talking to and will try again later in the week. Derek

[cad69]

Hi, I think I'll be looking at points, rotor or cap about now. Electrics failure is a lot more pronounced when running on gas. Keep us informed. Cheers Hugo.

[madmark]

replace the cap,rotor,leads,points,etc oftern a motor will give sypmtoms like carb problems but its the points etc!