Club 80-90 Forums

Don't let it take your attention from the problem but longer term it should help you get it all running right.

All put back together and what do you know now idling fast on petrol so got the engine warm and turned the idle down. Will run it up tomorrow and see what it's like on gas when I get chance. Can't remember how to tweak the gas vaporiser now though. Anyone have any tips?

Vapouriser has two screws one is the bias ( how much gas for any given suck) the other the idle bypass which give a bt more gas at idle, the bypass is often set low or zero and only affects idle.
Scresw are usually hex head

on mine idle bypass is a smaller screw but some are same size, get a pic up if not sure.

first thing to do is to turn them both clockwise until totally shut and count the number of flats ( 6 is one turn) write this down then return them to where they were.



Next is the power valve(s) in the pipes to the carb.
Mark them with a scratch or pen mark and count the number of turns clockwise to closed, then return it to where it was.

Play with the power valve first.

I think its running rich on gas, as you can smell gas in the exhaust so it definitely needs looking at. I assume your not meant to smell the gas...

mine smells of gas, gas has a stenching agent added so it will smell a bit

So the van will now, no longer idle on Lpg. Can rev it if I keep it off idle but it's just splutters and dies if I release the throttle. I'm guessing I need to adjust the idle bypass. It's never been bad to drive on Lpg so do t want to fiddle with much else if I can just sort the idle.

Possible you have other problems such as ignition timing, compression or air leaks so adjusting the carb or lpg may not be the right thing. If you do record where it was so you can go back.

It's running better than ever on petrol though. After redoing the carb and tweaking a couple things I had to lower the idle screw on petrol. Revs much better on petrol and pulls real nice under load.

Ok so try the idle bypass but as I may have said make a note of where you are and be sure you are moving the right adjuster.

And get a pic up of the vapouriser, power valve and general engine bay, help us to help you.

Give me 5 minutes, on my phone so need to work out posting images.

vapouriser looks crusty, get some penetrating oil on those adjusters.
top smaller screw is idle

OMVL by the looks

Sprayed some on after I took the photo. Thanks for the tip.

I assume screwing it in reduces the flow?

yes

That is an early omvl r90e, and looks like an early Gasure conversion? Also has old Pierburg twin mixer, but single screw power valve, so probably a VERY old system. They are really reliable vapourisers (sadly NLA), but it'll probably want a tweak if it's not been fettled for that long. Diaphragms and springs change in tension over time, and need compensating for. Or somebody's altered it. Or you've got an air leak. 5 minutes on a gas analyser to sort it.
Btw If I was going to the trouble of fitting a lambda probe, I'd pop an emmegas closed loop controller kit on, set it slightly rich, and leave it to look after the mixture itself!

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