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        General >> Problems >> Cleaning LPG vaporiser
        
(Message started by: Mike_Floutier on Mar 29^th, 2007, 10:55am)

Title: Cleaning LPG vaporiser
Post by Mike_Floutier on Mar 29^th, 2007, 10:55am

Hi,

I know a few of you run on lpg and I was wondering if anyone has needed to clean their vaporiser.

The problem I'm getting is occaisional missing/hesitation at idle/in drive (auto). It runs ok at idle in neutral and during other normal driving. It's done 200,000 miles with the conversion btw.

Here is a link to a pic of the vaporiser http://www.exhortations.co.uk/vaporiser.php

I'd love to hear from anyone who's cleaned this vaporiser; or any vaporiser for that matter.

Thanks

Mike

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Mar 29^th, 2007, 11:16am

hi mike

i had mine open just the other week. i've got a small pressure problem at higher revs.

anyway, all i done was removed all the screws to the 2 halves. opened it up a bit (on mine there is a nut/bolt holding the diaphragm in place). everything seemed in order, so i put it back together again. it seems a lot better now.

on yours, with the mileage, i'd say the rubber diaphragm has stretched a bit, thus you're down on pressure. also i was told that english gas is a bit more oily than scottish gas, so the inside might well be dirty.

you need to disconnect the power to the solenoid, start the car and swich over to gas. it should cut out after a few seconds. do this a few times to make sure you've cleared the line of gas. then take it apart. be gentle and don't pull it hard or you'll change the pressure setting. re cleaning. carb cleaner would do. just make sure you don't let it run down the tubes. block them with tissue (if you can see them). make sure it's all dry before putting it back together.

i was told some of the older ones had a drain, but mine doesn't have this.

you could take it back to the fitter and see what they say. new ones are about £150 +VAT upwards.

hope this helps a bit.
http://www.fordscorpio.co.uk/lpg2_3.htm

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Mar 29^th, 2007, 11:22am

hi there

another point is they're very similar to mains gas. if you know someone who works with gas heating, etc, they might know more.

hth

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Mar 29^th, 2007, 12:01pm

hi there

another point. make sure you check all the basic first. spark plugs, wiring, clean MAF, etc. then run it on petrol for a few miles to see if the issue is still there or not.

hth

Title: Re: Cleaning LPG vaporiser
Post by Mike_Floutier on Mar 29^th, 2007, 12:21pm

Thanks Scorpio_Man,

It runs fine on petrol - sorry forgot to mention it.

When you say "disconnect power to the solenoid", where is the solenoid? Will it be in the device upstream of the vaporiser or is it in the vaporisor itself?

Thanks

Mike

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Mar 29^th, 2007, 1:12pm

hi mike

if you look at mine in the like above, you can just make out the red live wire to it. mines looks like a small black box with a connector attached (a bit like a relay). there's also one down at the tank.

btw, when you do this work, it takes a few seconds for the gas to get upto pressure, so the car runs a bit rough for a bit. might even stall. mine was fine after about 20-30 secs.

htt

Title: Re: Cleaning LPG vaporiser
Post by Mike_Floutier on Mar 29^th, 2007, 1:37pm

Thanks,

I'll give it a try at the weekend.

Just one other thing that's troubling me - after refitting the coolant pipes will there be an airlock or will the air naturally find it's way back to the expansion tank?

Thanks

Mike

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Mar 29^th, 2007, 2:23pm

hi mike

i never took the coolant pipes off when i done mine. unless you're changing the unit i'd leave alone. you know what these cars are like for air locks! ;) the coolant only heats the bottom half and is sealed (i think) anyway.

if you take it off the car, you're best to 'crimp' the flow in pipe with a pair of molegrips or the like.

as i said earlier, i never took the top half completely off because of the nut/bolt in the spring. you'll see what i mean when you do it (if they're the same). be careful, as if you move the settings, you'll need to get it set up again at the fitter's.

Title: Re: Cleaning LPG vaporiser
Post by Mike_Floutier on Mar 29^th, 2007, 4:21pm

Thanks S_man!

Title: Re: Cleaning LPG vaporiser - maybe not!!
Post by Mike_Floutier on Apr 1^st, 2007, 11:52am

Well, I'm glad I didn't try to clean the gas vaporiser because as the stuttering on gas got worse I noticed that it was starting to stutter slightly on petrol as well - another fine theory out the window.

At least the fact that it was common to both systems AND much worse on gas was fairly conclusive:

1. It wasn't the gas system
2. It wasn't the petrol system
3. Probably was ignition OR inlet manifold OR egr.

I started by checking the plugs which were ok - tight and clean.

Then I took off the coils and HT leads - which I had replaced not so long ago (probably 75k in my case).

Here is a pic of the coil connections, side by side - http://www.exhortations.co.uk/coil%20pics.php .

I guess it must have been loose or something. I cleaned it up and opened out the plug connector to try and get a tighter connection.

A quick test and it seems ok but a couple of hundred miles tomorrow will say if it's really alright.

Mike

Title: Re: Cleaning LPG vaporiser
Post by Dave2302 on Apr 1^st, 2007, 12:58pm

Hi There,

I have been converting and running big boat engines on LP gas for years. The ignition problems you describe, always show up when running on gas first, then as they get worse they manifest themselves when on petrol. This is because the LPG is a very dry fuel so you really need a top quality spark to ignite it as opposed to wetter petrol air mix.

Regards Dave

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Apr 1^st, 2007, 6:08pm

hi mike

keep us posted on the results.

cheers

Title: Re: Cleaning LPG vaporiser
Post by Mike_Floutier on Apr 5^th, 2007, 9:34am

Just to update the situation, having cleaned the very corroded coil/HT lead connection there was no difference.

In fact it got worse and a couple of mornings ago it was missing once a second on petrol on startup but settled down after 10 minutes or so - enough for me to be able to work with passengers (switching from gas to petrol at lights so they don't get to enjoy the missing!!)

That afternoon I changed the plugs, cleaned the HT lead/spark plug connections and re-insulated the low tension leads to the front coil pack (which was much needed). I use iridium tipped plugs btw as they require a lower voltage and don't strain the ignition system a much as platinum.

I'd previously changed the plugs 10k miles ago and the old ones looked fine but hey I'm desperate.

It's now 2 days later and I've only had 2 misses. Now that's an incredible improvement but it still seems to be there. Maybe there's some other problem with igniting the fuel vapour. I guess it could be a number of things but I'll see how it goes for a while before starting to tinker again.

The car's done 250k miles. Could it be the Hego sensor (which is the original)?

Mike

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Apr 5^th, 2007, 10:48am

hi mike

could be. they last about 80k miles upwards. as usual, some go before and some just go on lasting.

if you can get an old one from a scrappy to get the plug (make sure it's a pre cat one as the plug is different). this makes it much easier to change to a universal one. you can solder the wires on the bench before fitting. much better to do that on a lpg car as most likely the wiring has been tapped into by the lpg system.

hth

Title: Re: Cleaning LPG vaporiser
Post by Mike_Floutier on Apr 14^th, 2007, 6:25pm

Ok, here's the final installment.

I was pretty sure it was an ignition problem so I tried running with one coil pack unplugged - sure enough it would misfire on the back one but not on the front.

So to check, I swapped the coil packs around. Guess what, the problem was still with the "back one" if you see what I mean.

So, I supected the LT wiring to the back one. I stripped it all out back to that long coffin-like black box with all that wiring, pulled everything apart and reinsulated it all. Still not working.

At this stage I'm pretty unhappy - have checked for leaks in the egr and inlet manifold so a bit puzzled.

Then I remember a figure on part of the site where it says the resistance in the HT leads should be around 20k ohms or something so although I'd changed them last year I thought I hadn't much to lose so I put the meter on the one fed from the back coil pack. No continuity at all!

Thank You Lord! £15 and I'm back in business.

And thanks to you guys as well!!

Mike

Title: Re: Cleaning LPG vaporiser
Post by scorpio_man on Apr 14^th, 2007, 6:35pm

well done mike. :)