how does the choke work on petrol and gas?

[ermie571]

Ok folks - as the title says, in words of few silly-bulls (Blackadder), how does the choke work?

How do I check it?

How do you know if it is coming off too early....I feel that it may be as van will stall at the second set of lights, but be ok by the third!!

On start up, its lumpy, and won't hold the revs without a foot on the pedal.

2.1 running carb. Checked the vaccuum pipes coming off my carb....one goes to the dizzy, the other goes to the big air tube on the right. Is there another one that needs balnking off?

Engine is sweet, and will be going back for its 500 miles service so can ask them to check it over then.....just wondered if there was anything simple I needed to be doing?! (emphasis on the simple, boys and girls)

Also - once it is warm. it will occassionally decide that it wants to idle at 40- 600 revs...it will hold it, but thats not right, and I give it a bit of gas to get back to the 800 revs mark. Then it will be fine for ages. Is something loose? A bit of knowledge before I take it back for its check-up would be great.

Em
x

[clartsonly]

I did all of this with mine and again cleaned out the breather then shoved a big spring down to the kink in the breater pipe to keep it forced open adn the problem seems to have gone away, does yours have a idle stabilisation unit? if it does disconnect it to see if it works better without it joined up

[ermie571]

Thanks...will check the breather tube - that is easy!!

Will check the ISU too...also easy!!

thanks
Em
x

[clartsonly]

I will point out as well that even after doing all of this it didn't seem to run too well just being started on the drive and idling until I had taken it for a run. but I am quite confident that it doesn't constantly cut out everytime I drive it.

I also have a bit of a funny with mine I upped the idle speed to about 1100 but it idles at about 800 unless I have just finshed a long drive so it is fully warmed up, then it idles at 1100 which is a bit irritating.

[phredd]

Ermie
I was, and still am under the impression that the Gas side of the engine does not use the Choke.
I will stand corrected if you or any wishes to correct me

I always start on Petrol for about half a mile then switch to gas. Seems to do away with the lumpieness.

Phredd

[toomanytoys]

Is this still on petrol??
The choke has no affect on LPG apart from not allowing enough "depression" into the inlet for the vaporiser to "see"... thats wht on lpg the throttle should be pressed slightly to allow the choke to open a bit..

check for any intake leaks from carb to venturi

[ermie571]

Hi folks - thanks for the answers. Didn't think the choke had any affect on gas...but wanted to make sure!

yes Si, on petrol too.. goes as follows

Petrol
Press accelerator to open choke
fires first turn
hold the revs - foot about halfway?
revs losw, lumpy....tries a bit, react to engine with foot...
revs slowly climb, suddenly catches then its away.

does very similar on gas - have to hold it on the pedal too...

oh- will check fuel filter...maybe clogged I suppose...another easy check!

Thanks all

ps whats a venturi?

Em
x

[Ian Hulley]

On our DJ with lpg and carb from cold you press the pedal to the floor, release it slowly, turn ignition key and it starts 'on choke'. Left alone after a few minutes the revs drop as the auto-choke detects heat and switches off. You can also 'knock the choke off' by a quick blip on the accelerator pedal.

That's how our's works anyway

Ian.

[clartsonly]

Petrol
Press accelerator to open choke
fires first turn
hold the revs - foot about halfway?
revs losw, lumpy....tries a bit, react to engine with foot...
revs slowly climb, suddenly catches then its away.

I am no professional but that sounds like rotor, leads, advance / retard or timing I realise that is no help but are you sure it is adjusted properly? maybe still also related to idle stabiliation unit.

[Ian Hulley]

ps whats a venturi?

Em
x

Em, a venturi is a narrow opening through which one gas ... say for example petrol vapour ... is drawn by the rushing past of another gas ... let's say it could be air ... thus creating a combustible fuel/air mixture.

Ian.

[ermie571]

Clartsonly - thanks for that.....will be checked. But all very recent on that stuff....thanks for your comments though!

Ian...

thanks for your definition of a venturi. Next question

check for any intake leaks from carb to venturi

so where do I need to check? I now know what a venturi does...and as it involves air and fuel I guess the carb....but Si says between carb and venturi?

thanks again....a bit dim today...

[Ian Hulley]

Personally I'd check the advance/retard hoses and also the plugs, leads, cap & arm .... when were they last replaced. Are they the same carp Unipart plugs in your Elite DJ as they are in mine ?

Ian.

[ermie571]

Ian - just rung elite....would have changed the plugs....so will check....may be the triple point ones....will get John to look! But leads and dizzy cap would only have been changed if knackered.....and they had only been on a couple of months, so my guess is that I have got the ones I had on before.

What plugs do you recommend?

Will check the vaccum hoses and connections...as advised.

thanks
Em
x

[Grun]

Ian wrote.......

Em, a venturi is a narrow opening through which one gas ... say for example petrol vapour ... is drawn by the rushing past of another gas ... let's say it could be air ... thus creating a combustible fuel/air mixture.

...........and there's me thinking it was some Italian geezer


Giovanni Battista Venturi, (1746-1822), an Italian physicist

What a mistaka to maika

Mike

[Ian Hulley]

Ian wrote.......

Em, a venturi is a narrow opening through which one gas ... say for example petrol vapour ... is drawn by the rushing past of another gas ... let's say it could be air ... thus creating a combustible fuel/air mixture.

...........and there's me thinking it was some Italian geezer


Giovanni Battista Venturi, (1746-1822), an Italian physicist

What a mistaka to maika

Mike

Now you're just plain showin off ! (or at least Wikipaedea is )

Ian