Choke valve jiggling needed to start the car

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kiii
Posts: 1
Joined: Mon Sep 28, 2020 6:22 pm
Car(s): 79 Capri MK3 2.0

Choke valve jiggling needed to start the car

Post by kiii » Wed Sep 30, 2020 5:39 pm

I bought a Capri recently, it has a single venturi carb on it
It worked very well when I bought it, started up on a dime every time, no problems
But slowly over the last few months its become hard to start, cranks but doesn't actually start, this is issue is worse when cold

What does help it run every time, is whilst the starter is turning, to manually jiggle the choke valve on the carb. The engine does start then. This makes me think it's just the air/fuel ratio getting upset here.

How would you go about fixing this? I'm assuming this requires some tuning to the carb, which i'm assuming you can do with just the screw?
But why would the carb slowly become more and more 'uncalibrated' over a few months. Is there another issue I should be looking out for?

Thanks

STEVEW
Posts: 125
Joined: Sun Dec 30, 2018 10:10 am
Car(s): Ford Capri 2.3S
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Re: Choke valve jiggling needed to start the car

Post by STEVEW » Thu Oct 01, 2020 7:37 am

Hi kiii

I obviously don't know your mechanical experience so please don't feel insulted if my following post seems too basic for you.

Start simple - so to speak.
In what condition is the air filter?

Before playing with the fuel/ air settings do a simple "tune up".
Check:
  • the condition and gaps of the plugs and points
  • ignition timing
  • check valve clearances
Once your satisfied with the above then you can start to find the fault.
The colour of the plugs, for example, will tell you a lot.
All the best,
Steve

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pbar
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Joined: Thu Jun 07, 2012 6:29 pm
Car(s): Capri 2.0 Laser, frequent driver.
Location: North-West

Re: Choke valve jiggling needed to start the car

Post by pbar » Mon Oct 05, 2020 4:02 pm

Sounds like the choke flap may be sticking, and has progressively got worse as time goes by. It should be fully closed on a cold start, would be a pain to start if it's stuck open or sticking. So I'd check that when convenient, next time you cold start. It's definitely the first thing I'd check before I started to mess elsewhere.

If it is closed then I'd go through service/ignition parts, such as points (assuming it has them), ignition parts such as these wear down over time by their very nature. Rotor arm, dizzy cap, condenser, spark plugs, all cheap and easy to replace, change one component at a time (although I'd do the rotor arm and cap together) then you can see what a difference each one makes, if any of them have been in there for a reasonable amount of time then it usually makes a noticeable difference.

'Messing' with the choke flaps as you start it may help as it is masking the real issue, which may just be one of the parts such as those above.

You might just find that if you do a service and change all of the above then your car will be back to how it was when you got it, especially if you've done some miles over the past few months.

Good luck. Make sure you post back any results, good or bad!

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