Ae71 4ac idling rough

[succulent eye]

Hi all and thanks for the help In advance. So where to begin. Plain and simple the car is idling very rough, it seems to have the choke getting stuck on or be running far too rich. I can unplug the power to the choke and the car slows and stalls, also I can lean the idle mixture to nothing and it still runs. I'm somewhat confused what it might be so I've come to the geniuses to see. Thanks for the help in advance. 

[altezzaclub]

I haven't worked with 4A-c motors, except to throw them out.. but if you take the air cleaner off and look down the carb, does the choke flap open as it warms up??

I expect that the bimetallic spring closes the choke when the car is switched off, and when the ignition is on it slowly lets the choke flap open up. Look down the carb before you start the car, check the choke flap, and keep an eye on it as it warns up.

 

[succulent eye]

Thanks heaps for the quick reply. I had the air filter off and the car running to see what it was all doing, the choke flap is open when it's warmed up so it's got me stuffed what it might be. I find it odd that I can completely lean the idle out to nothing at all and it still doesn't matter. 

[altezzaclub]

OK, the problem isn't the choke sticking closed.

Somewhere in the carb there is fuel pissing into the motor where it shouldn't. One spot would be the needle & seat valve that sets the fuel level in the bowl. That would make it rich all the time, so what sort of L/100km are you getting?

7L/100km on a trip would be fine, maybe up to 9L/100 around town.

[succulent eye]

Yeah that's what I'm starting to think too. I've only had it for 3 days so haven't had a proper tank through it, just filled up now so I'll keep an eye on it. I've worked out that say I drive to the shops it goes like a pig and stalls then I stop for 10 minutes doing the shopping and it runs fine for the first little bit then goes back to a pig. It's a constant routine of that as far as I've worked out. 

[succulent eye]

Ok so another update, I've checked the little float level glass thing on the front of the carby and it's sitting just above half. So this tells me that the float level is good. Is there a certain vacuum line I'm meant to have hooked up or not hooked up ? I can try get some photos of the carby if it makes it easier ? 

[rebuilder86]

the fact u can screw the idle mixture screw all the way in, means its running off the primary main jet instead of the idle circuit and slow jet.
This is a problem.
It needs the choke because at idle, the suction is normally caused by static pressure suction, and there is none of this at the primary main jet, unless the choke flap closes.
Sowaht you need, is to check the idle circuit is operating. 
The little solenoid on the side of the carb, next to the choke system, should click when the cars igniton is turned to on. If not, somethign is wrong with the solenoid or the electrics.
If it does click, then u can suspect hat the carburettr idle circuit is blocked. This is very common, as the jet for the slow idle circuit is incredibly small, and one piece of rubber from a fuel hose deteriorating is enough to completely block it.

i suspect if u take the air filter off, and look down the carb with the engine idling, push the choke flap open quickly, u will see fuel running out of the main jet onto the throttle flap. If u see this, then thats the probem.

The idle circuit needs to be repaired and the  base idle screw set back to near closed.

Edited March 14, 2018 by rebuilder86

[succulent eye]

Here's a video to help show a bit of what it's doing. Hopefuly it works. I tested the solenoid thing on the carby and it's working fine so my guess is it's blocked. Any recommendations on how or what to do ? I've had carby cleaner blasting it through it but still no luck. If you spot something I'm meant to have hooked up different just shout out and I'll change it. Thanks heaps for your help. 

[rebuilder86]

yep definitely need to clean out the idle circuit

one thing u can attempt, is to undo the idle mixtrue screw,, and spray carb cleaner through that wiht as much pressure as possible. that may push the particles back out the jet into the float bowl, but its likely itl jstu end up back in there.

Take the top of the carby off, find the slow jet which is visible top down, this diagram is drawn as if the 2 sides of the carb are cut in half and pivoted around the centre,   for clarity.
If u take the top off the carb, the idle jet is visible and is orientated as shown in the diagram. Up down. wheras all other jets (except the power jet in the middle of the float bowl) are sideways. The idle fule, must pass through the primary main jet before it is alowed to pass up through the idle jet, where it is then mixed with idle bleed air.
there is also a secondary slow jet, and this wil be on the same side of the carb as the secondary barrel. don't worry abotu that one so much.
To get the slow jet ut, undo it with a screwdriver, then stick a pin down the centre of it and try to angle the pin so it grabs onto the wals of the jet and pull it up.
When its out, spray everythign with carby cleaner adn blow ackwards through the jet to clear it out.

[rebuilder86]

read this about the 4AC carb
http://members.toast.net/ahines/Carbie_notes.htm

[succulent eye]

I did what you recommended and it's fixed. Thanks so much for your help and sharing your knowledge, I'd have been stuffed without it. 

[rebuilder86]

Oh thats excelent mate. So stoked it was that simple.