High fast idle

[v76124]

Hi everyone,

I'm new to Fiat ownership (or any classic/old car ownership). I got a 76 124 as a daily driver last week and its been a blast to drive so far other than a small issue. I'm in the Bay Area (Northern Cali) so its never too cold (prob low 40's at its coldest) if it makes any difference. The car has the 1800 with a 34 ADF carb with automatic choke and stock air filter.

When I start the car, I pump the gas twice and it fires right up but revs at 2.5k rpm and slowly goes up to 3k for a full 2 mins or more sometimes. I thought you could disengage the fast idle by stabbing the throttle quickly? This doesn't work in the beginning, but it will come down to normal idle speed (around 850 rpm prob) after a few minutes.

Sometimes it comes down to normal after a good stab of the throttle but goes back to 3k rpm at the first stoplight (about 150m down the road) and then goes down after another minute or 2 of driving. This gets annoying real quick since I live in a residential neighbourhood and don't want to be the moron revving his engine in the mornings

I have also tried starting without hitting the gas, it catches and dies (or stays on sometimes). I tried starting with the throttle fully open and that seems to kinda work? It goes to fast idle but comes down to normal if I stab the throttle (but not all the time).

So, I'm having a hard time understanding how not to be revving at 2.5-3k rpm in the mornings and annoying my neighbours. I thought the choke was only for 10 secs or so? I watched some videos of users adjusting electric chokes with notches in the spring - mine looks like a hot water fed choke (34 ADF) so haven't tried that yet but it only has 1 tick/mark.

Is there a way of adjusting the fast idle to not be so high?

[Nanonevol]

You can adjust the water choke for your warmer climate. I haven't done it and you may have to experiment but you loosen the three screws and turn the choke one way the other.

[blazingspider]

There are 3 sub systems for the automatic coke. The choke flap which is opened and closed by the bi-metallic spring dependent on temperature, the fast idle speed which is set by a screw riding on a spring loaded stepped cam that holds the throttle lever open when activated and the choke pull off which is operated by vacuum and pulls the choke flap back against the spring tension.

To me it sounds like your fast idle cam may be all gummed up as you should be able to consistently lower the fast idle speed by depressing the accelerator pedal. If it checks out OK then you need to adjust the fast idle speed and maybe the spring tension on the choke flap.

You can gain access to the spring loaded fast idle cam by removing the 3 screws for the coolant capsule and swinging it out of the way. No need to disconnect the coolant lines or worry about coolant spilling out of the capsule as it is self contained. Once out of the way you will see the fast idle cam inside the choke body. Make sure it's clean and operates freely. When you put it back together make sure the bi-metallic spring on the back side of the coolant capsule fits into the notch for the choke flap arm.

Once back together you can set the fast idle speed by turning the long adjustment screw that disappears into the choke body. Turning it out will decrease the speed. The spring tension for the flap can be adjusted by rotating the coolant capsule. One way will increase the tension and will make the choke flap stay closed longer and the other way will lessen the tension and make the flap open quicker.

You need to make the adjustments on a cold motor with the choke engaged by depressing the accelerator pedal and as all 3 interact with each other you may need to fiddle with them all to arrive at your optimal configuration. Good luck!!