Hi all. I have a 1979 Mark 2 Ford Escort with the 1.6 L carbureted engine. It has to be choked for it to start but once it's started and has been turning over for a few moments the choke can be eased off gradually and the engine will idle nicely. But upon pressing the accelerator, even slightly, the engine wants to stall, especially if you stab it too quickly. If you leave the choke on a little, it tends to rev up must more easily, but take the choke off and it's very temperamental. The problem lessens when the engine is warm.
 
Can anyone think what the problem might be? I've tried turning the mixture screw to make it run richer (figuring this is what the choke is doing) but it doesn't seem to help much. I'm guessing it will be something to do with the carburettor, i'm just not sure what. i have limited mechanical experience but i do have common sense and i'm eager to learn more.
 
I'd really love to finish this car and get it registered. Can someone help me?

Buy some carby clean.
Spray it carefully around the base of the carby and any potential points of vaccum leak,  it the idle speed changes you have found a leak.
 
Otherwise give the carby a good shot down the throat and make sure you blast out the small air bleeds inside the thoat at the top.  Then readjust the idle speed and mixture screws for the smoothest idle.
 
 

Hi
Thinking it could be blocked accelerator jets or damaged accelerator pump diaphragm. Normally your motor would receive an extra dose of fuel via both items, if either doesn't work then your motor will get a big dose of air from the butterfly opening but no corresponding fuel, motor goes v lean and stalls.
Which carby do you have? Did you do anything to the car before this started happening?

One easy way to check to see if the accelerator pump is not working or discharge is blocked. Switch the engine off, remove the air cleaner look down down the carby opening and press the accelerator. You should get a nice steady stream of fuel coming out of the accelerator discharge jet. If not, the jet is blocked or the pump is not working.

Upadte. Well, I've completely re-kitted the carby and adjusted the fuel air mixture and idle. for mixture i turned the screw all the way in, and then it seems to be best at about 3 1/2 turns out.
The issue is still present, unaffected. Still stalls on throttle and the problem is lessened with the choke on.
Any ideas?

What carburetor do you have? 
Have you searched for a vacuum leak as suggested? Carby cleaner or aero start are both good for this and as said above spray it around all your hose fittings and at the base of the carby while at idle and see if you get a rise in revs.
Bad spark timing and weak spark can also give you symtoms like these, Have you adjusted/ checked the points ( assuming your car hasn't been converted ) and timing lately?
If it is spark then what you do to the fuel side of the deal isn't going to do much to change things.

As for spark and timing I think it's definitely worth checking out. I'm positive now after rekitting the carby its not a vacuum leak, but i'll get some carby start and test for that today anyway just to rule it out. i've been laying off doing anything about timing because I don't understand much about it. I guess ultimately it's a good opportunity to learn about it, just as the rekitting process taught me how a carby works, so even though I knew it may  not fix the problem, I did it anyway because I wanted to learn this and did :)
 
i know that timing is the point during the piston's travels that the spark plug fires. if the spark isn't syncronized with the up and down movement of the pistons correctly, the engine won't run correctly or won't run at all. that's about all i know. but i'm having trouble understanding why bad timing would cause these symptoms. if the timing was off, I would assume that the engine wouldn't idle correctly and wouldn't rev up providing the choke is on. can someone clarify for me why bad timing might make the engine behave like this?
 
thank you everyone for your help so far! I greatly appreciate it

It most probably is fuel side related but if you have poor spark / bad timing you are giving a gut full of fuel and air to the motor when you open the butterflies, badly timed and a baby spark to ignite it can cause the motor to flood and stall.
The points and timing needs checking probably every 5000 ks for correctness ( by the book anyway ).
This is one of the biggest advantages with electronic ignition because points wear quickly, and EI doesn't.
Definitely check for vac leaks first, especially the two larger hoses that run from the manifold to the brake booster and to the sump valve.

When checking the timing make sure the timing mark advances when you rev the engine. I agree with Mickos, it sounds more like fuel problem. Did you check for fuel coming out of the accelerator discharge jet when you open the throttle. If zero discharge this will give you a big flat spot on acceleration and it might also stall the engine.
The way the carby works is as follows-
At idle you have fuel coming out of the idle discharge hole which is below the butterfly and controlled by the mixture screw. Above this you have what is called progression holes, the purpose of these holes is to give a smooth transition from the idle discharge hole to the venturi discharge nozzle, which is connected to the main jet in the carby which supplys all the fuel for running the engine. On gentle / hard acceleration, the accelerator comes into play preventing a flat spot and possible stalling.
You need to check if the accelerator pump is working and fuel is being discharged into the venturi. The venturi discharge nozzle is not blocked. Check the timing is set correct and it advances.