4.6 doesnt like to idle on gas

ckc100 · Sep 21, 2010

Any one out there had issues with there 4.6 with a gas conversion not liking to idle on gas.
This thing runs perfect on petrol hence I started having issues with the gas a few months ago, but as it runs on petrol fine I have never got round to looking into it.
I have had a fiddle with it today but nothing obvious wrong with it.
It starts on petrol switches fine on to LPG which apears to be single point into the air manifold, it feels okay when cold for a few mins, then it when drawing up to junction it just dies unless you catch it.

It runs good when just cruising on gas it is fine, but if you boot it up it will stutter and fart about then take off.

Any ine got any ideas.

rewmer · Sep 21, 2010

Tired diaphragm in your vaporiser. Gas delivery pressure could be down. Don't suppose you have any software with the system to read the pressure ? If not, try screwing the screw/ bolt in the centre of the vaporiser in and see if that helps. Don't go to mad with it.

ckc100 · Sep 21, 2010

Hey there, Thanks for the tip, I have had look under the bonnet but am unsure which screw this would be as the one I would expect it to be does not look to be adjustable, but could I be looking at the wrong bit, I have attached a picture of the bit I am looking at.
Not sure if this is the vapouriser as it has copper piping in and out to another part.
I will post a bigger picture if this one goes on.

ckc100 · Sep 21, 2010

Picture with a few more parts in it.

rewmer · Sep 21, 2010

The second picture looks like the vaporiser. It should be roundish in shape, and in the centre of the face there should be a screw. Post up another couple of pictures of silver part.

ckc100 · Sep 21, 2010

I have been out and taken another few pictures, here is one of the "vapouriser" It does not have any screws in the middle but down the side of it which I have tried to show in the second picture there is a one screw higher up the side, and one lower down which looks like it has a spring on it as in the idle screw of a carb..

rewmer · Sep 21, 2010

I would wager the recess arrowed has the adjustment screw. I dont recognise the make of Vap so it may be worth doing a bit more reaserch into it to find out for definate how to make adjustments,

Willos · Sep 21, 2010

When did you last have the vapour and liquid gas filtewrs changed ? The liquid is in the first photo the gas should be between the vapouriser and the inlet manifold

ckc100 · Sep 21, 2010

I have had the car 6 months now and never changed any filters, it was supposed to have been tuned about 4 months before I bought it.

Does the bolt on the end keep the lid on them where you would slacken and pull out a filter?

There is a funny shaped unit just infront of the vapriser when I have started looking.

I have been out tonight all ready and adjusted the idle screw a little, which as made no real difference to the idle on gas but it certaily has improved the acceleration and pulling when you put the foot down when running on gas. Infact I would say it is pulling as good on gas as it does on petrol now.

v8hotrodboy · Sep 25, 2010

My advice is to get the lpg serviced by a specialist, as if you muck about with it to much it can cause all sorts of probs. Had my single point checked adjusted etc by my local lpg guy and he told me to leave well alone if you dont know what your doing. Wasnt expensive and runs spot on.

ckc100 · Sep 25, 2010

To late me being a ex diesel fuel injection specialist in my long and distance past I just had to have a fiddle.
So now got it running good idle until up at full temp then the idle slows. All though it now running with good power and pulling when hot cold or anything when on gas so it has improved.
As for the filters I will look into them when I get home next trip.
Thanks for all the adivce gents, I might have another fiddle to get the idle tommorrow if the rain stays of for at least 10 mins.

4.6 doesnt like to idle on gas

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