Yet another carby question

[Meteor]

Recently been having some probs with the sierra with the colder weather coming on. Starts and idles fine when cold, but for the first few minutes when you put your foot on the accelerator the thing just splutters and dies. It's been recently reconditioned, so i'm not sure if it's just an adjustment that has been screwed up or something else that needs fixing. I've done a search and nothing seems to fit the symptoms.

[christover1]

Recently been having some probs with the sierra with the colder weather coming on. Starts and idles fine when cold, but for the first few minutes when you put your foot on the accelerator the thing just splutters and dies. It's been recently reconditioned, so i'm not sure if it's just an adjustment that has been screwed up or something else that needs fixing. I've done a search and nothing seems to fit the symptoms.

my zook started doing that, too, as soon as the cold weather came.
With mine the auto choke wasn't working.
The spring on the mechanism was shagged and the actuator connected to it was siezed, so choke wasnt choking. Fixed that and problem went away.

I did a carby kit thru mine, it didn't include any choke bits, so maybe I should have got a major kit, not a minor one?

christover

[Pinball]

As christover alludes, sounds like the choke hasn't opened sufficiently, could be poor operation (check water flow through) or could be the engine just isn't up to temperature when you want to go...

Spock

[Meteor]

Water flow should be top notch, just been reco'd to take care of the old 3500rpm idle trick, and a new radiator/coolant etc went in not long ago as well. Is there any adjustment on the carby that i can fiddle with to see if i can fix it?

[christover1]

Look at the position of the choke when cold, ie first thing in morning, then look again when its hot, and see if it has changed position.

The opening and closing of choke is adjustable, with a screw somewhere, but is also dependant on the positioning of the spindle, nylon gear thing.
some people assemble these wrong, and choke dont open or close fully.

christover

[christover1]

this may help ?

[Meteor]

Brilliant, thanks for that. I figure it's something to do with the accelerator pump, not the choke. ie it idles fine, just splutters and dies when the accerator is pumped. I reckon the acclerator pump has gone a bit out of whack when the carby was recon'd and it's dumping too much fuel in when cold and making the engine stall. I've got NO idea how to fix it though...

[christover1]

Brilliant, thanks for that. I figure it's something to do with the accelerator pump, not the choke. ie it idles fine, just splutters and dies when the accerator is pumped. I reckon the acclerator pump has gone a bit out of whack when the carby was recon'd and it's dumping too much fuel in when cold and making the engine stall. I've got NO idea how to fix it though...

you can check the accelrator pump, by takin air box top off, look into carby throat, then floor the accelerator, and you will see a spurt of fuel, if its working. a light mist would be not enough fuel.
worth a look into.

christover

[Meteor]

Yeah, it's definately working, i just think that when it's cold it's working too well and flooding the little engine. Had the air box off, pulled the accelerator cable and everything is good (the engine was already warm), get little squirt from the accerator pump and it revs fine. I pushed the accelertor pump by itself and i did exactly the same as it does on a cold start, dropped revs and died.

[lay80n]

Yeah, it's definately working, i just think that when it's cold it's working too well and flooding the little engine. Had the air box off, pulled the accelerator cable and everything is good (the engine was already warm), get little squirt from the accerator pump and it revs fine. I pushed the accelertor pump by itself and i did exactly the same as it does on a cold start, dropped revs and died.

Pushing accelerator pump without opening throttle butterfly will just make the motor run rich, of course it will die . The accelerator pump is designed so that when the throttle is opened (more air allowed into motor) the motor will smoothly and easily accelerate. Pumping it without allowing more air into motor will just make it rich, and splutter splutter. Many older motors will run pretty average with a few Kays on them and cold. If it is running good and goes fine when warmed up, fix the choke and let it warm up properly. Flogging a motor when its cold (and therefore parts not heated and expanded to working size) is a good way to shorten the motor's lifespan. Listen to a cold motor rattle if you just turn it on and rev it, as compared to a motor at opperating temp. Also driving before motor wamed up will chew fuel too.
Layto....

[christover1]

Yeah, it's definately working, i just think that when it's cold it's working too well and flooding the little engine. Had the air box off, pulled the accelerator cable and everything is good (the engine was already warm), get little squirt from the accerator pump and it revs fine. I pushed the accelertor pump by itself and i did exactly the same as it does on a cold start, dropped revs and died.

When you push acc pump without the accelerator, its gets full fuel, but no air, as acc butterfly isn't open, so yes it will stall.

If you rule out carby issues, then check spark, weak spark is easily put out by cold fuel.
I'm out of ideas, all I can say is good luck, hope ya sort it out.

christover

[Meteor]

I was expecting the motor to die with the accelerator pump being exercised, was just trying to explain the symptoms a bit better. The accelerator isn't being jumped on in the mornings, just enough to move out of the garage will set it off. Just seemed weird it started on the first cold morning after having it reco'd, it's never done it before, i thought it might have been a wayward adjustment somewhere. Thanks for the help anyway, if i can't figure it out i'll buy a stopwatch and wait 2 mins before going near the right hand peddle

[JrZook]

Brilliant, thanks for that. I figure it's something to do with the accelerator pump, not the choke. ie it idles fine, just splutters and dies when the accerator is pumped. I reckon the acclerator pump has gone a bit out of whack when the carby was recon'd and it's dumping too much fuel in when cold and making the engine stall. I've got NO idea how to fix it though...

So u sure its too rich ie flooding wen it is cold??? Could possibabily be too lean. Start it up cold in the morn with the airbox off and slightly open the butterfly till its starts the spultter and die then quickly cover the top of the carb with ur hand and see what happens. If it picks up then it is running too lean when it is cold and the choke flap will need the be closed up a lil more.

[Meteor]

Don't know how i've done it, but my blind fiddling with the carby has got it purring along. Now if i could do the same with my girlfriend....