LPG Problem

B

bluemouse1006

0
Hi:D
My Commer (betty) has LPG conversion and im having problems as always . all the solenoids etc are working great,i can set the gas up to run at idle all day then when you drive it its like its running out of gas, i can drive along with the engine cover up and richen it up so it runs ok on the road but then its too rich on idle so stalls. any one know anything about LPG ? is there out there a vacuum operated regulator type valve between the gas pump/evaperator and the carb that could help because at he moment there is an adjustable knerled nut valve [?]or do i just need to set it up on the gas analyser.
the fuel ring isnt on top of the carb and is on the other end of the airfilter extention dont know wether this is anything to do with it but it seems to have been like that for years

would appritiate the help

cheers
Amos :D
 
The vapouriser is usually on top of the carb. On my wifes car, it kept coming loose and rotating, stopping it drawing in gas.
Also, check the valve clearances, as they tend to close up with gas, reducing the compression and thus amount of fuel drawn in.
Probably worth getting it set up by an LPG garage, if you've been twiddling with the knob :I
 
Hi, it is the *mixer*, not the vapouriser that sits on top of the carb, so called because it mixes the gas (after it has vapourised!) with the air before it enters the engine. The vapouriser is the (normally round) unit that will have 2 water connections (to stop it icing up) and 2 gas connections (one inbound from the tank, and one large outbound one to the carb).

I always use this method to set up my LPG systems - it's been good and worked for me every time (blatantly stolen from another forum!).

From my experience:
Small brass screw with straight head is the idle mixture. Lean in rich out.
Black plastic adjuster (sometimes larger brass screw) is the diaphragm pressure. lean in rich out.
In-line (in the big gas hose) sprung screw is high-range adjuster.
If you can't work it out another way, try this:

-Turn the 2 screws on the vapouriser (not the mixer!) all the way in, the in-line one all the way out.
-Run up to normal operating temperature on petrol.
-Undo the brass one by 3 turns and attempt to start up. Keep loosening by 1/2 turn until an idle of 1000rpm is obtained.
-Next, still at idle, undo the plastic diaphragm screw until the engine note changes, then tighten up by 1/4 turn (i.e have it as far undone as possible without it changing the idle speed)
-Now get someone to hold the throttle so the engine is at approximately 3000rpm. Do up the in-line sprung screw until the exhaust note changes, then back off by 1/2 turn.

Et voila, a fool-proof way of tuning a gas system, never failed me yet and I've done it on 2 engines with 2 different vaporisers. They're all basically the same just the adjusters are in different places.
 
mr or mrs Gimp [}:)]

many thanks for your advice i will have a go at adjusting the bits and bobs and if i get stuck then take it to the peole in the know.i realy want it to run ok on LPG as is so much cheaper than 20ish mpg on petrol .

regards
Amos :D
 
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