Club 80-90 Forums

The only adjustment in the Carb I made, which I can see effecting this, was to the vacuum controlled aspect of the throttle flap. Should be a 40thou gap either side of the plastic lug. Mine was way out, which was holding the revs high. I reset that to 40thou either side as per the video in the wiki I found.

First try closing idle bypass to zero in case its now rich, if not return it to 1/2 turn where you started.

then close bias ( large screw on vapouriser) and count flats write it down ( not turns because it's sensitive so better to count flats) then open it, I would start at 6 flats which is 1 turn.

if it still won't run keep opening power valve until it runs

you really need to set it up properly, better to be rich that lean,
if you get more that 18 mpg (20 mpg on a run) it's lean IMO


When I had a single power valve it was 4 turns to run right with six flats on the bias.
I have returned to a twin screw power valve which runs on 3 turns.
this is no guide though as your vapourise may be different.

Thank you so much itchy, I'll report back!

I have been playing with mine for about 2 weeks, I have a co meter and an air fuel gauge and I still can't get it spot on cold and hot.
Just put my bias to 8 flats because it was gutless cold.

I think there's too much emphasis on the idle bypass screw here, which is a secondary adjustment only used if it ends up too lean at idle after the main "bias" adjustment is correctly set, or if starting is poor on LPG due to lack of positive pressure to deliver priming gas. At the very low bias settings mentioned, this would probably be the case, and would need a little bypass to help things along.
Start with the idle bypass closed (and it's almost never necessary to open more than 1/2 turn). On an omvl r90e the bias often ends up between 1.5 and 2.5 turns out from closed to get a good idle, then rev it to 3k+ and screw the "power valve" in until engine note changes/dips. Back off 1/4 turn. This is a basic setting to get it running close to correct. The rest is best done by gas analyser and road test.

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Thanks Andy, once I can get it to idle in any form ill make sure I do that

Joy, ran out of petrol sat on the drive!

The van used to start on Lpg in this sort of weather. So I've turned the bypass (small screw) to zero and the bias (big, sprung screw) to 2 1/2 and opened the power valve up, tried to start it. And not even a splutter

Although I can't check whether I have a definite spark as I have no assistant, hall sensor connection is temperamental you see.

I know somebody who thought their lpg was faulty when in fact the tank was empty.

I filled the lpg tank and drove 25 miles before putting it on the drive and stripping the Carb so I'd hope it's not empty.

On another note, the large screw (bias) was out nearly 5 turns before I adjusted it

Get some petrol in it and start on petrol, quicker than checking if you have ignition and the great thing about dual fuel.

Suddenly you tell us you have a bad connection on the hall sender, anything else you forgot to mention?

Get somebody to turn the key to position 1 while you are at the carb, you should hear solenoids click and get a puff of gas

I have known them to need 5 turns, it all depends on the spring tension inside, which can change over time (many heat cycles, I suppose). Have you got a good seal around the mixer to carb? Any leak there will play havoc with your gas draw.

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I'll check that seal. That's the only thing I've really disturbed when sorting the Carb I guess.

There is a rubber seal between the induction ring, and the carb but nothing to seal between the filter head and the ring.

Ill make sure its well and truly sealed this eve and try some more tweaking. Battery is currently on charge as its taken a hammering the last couple days.

I'm going to follow that procedure too
I have no issues on petrol plenty of pep, but gas starts to run into problems at 2100 rpm then the whole thing feels like its running on three.

Make sure you tightened the pancake to air filer hose clips too, I have left them loose before and had problems

check your airfilter isn't contaminated with oil, that will stop it running on lpg

Any more than 1.5 turns on my bias is veey rich but it is 10 years old now and so spring may be slack.

Why would anything in the system before he introduction of the LPG effect it? Is it because the LPG relies on the vacuum in the intake to pull it down through the carb? the vacuum pipe from air box to carb had split so blanked that at the carb. should I replace it?