Tuning Have 2 problems that need help on

[jota69]

I have two problems with my car, first my car's idle is really bad and I have tried to adjust it but it would not idle smooth. It runs fine but when I come to a stop it will idle bad and sometimes turn off.

Second problem is my left turn signal does not workand would like to know whatto check to make it work

 

[Indyspecracer]

I'm not all that familiar with these cars, but I will offer a few things to look at.
On the idle, timing could have slipped, also the butterfly shaft in the carb could be worn and leaking air. Somthing to check on the turn signal, find the flasher unit, unplug it and put a voltage meter on each of the (probably 3) connectors that it plugs in to. One will be earth ground, the other two will feed the turn signals. You are trying to make sure that you have power two these terminals as you actuate the turn signal stalk. If you get power to each, it is a bad flasher unit, it you get no power when stalk indicates left, likely a bad turn signal switch.

 

[littlemouse]

Worth checking whether you have a bad earth on the indicators, had a similar problem on mine and it was a simple case of just replacing some of the earth cables.

 

[jjacob]

jota69,

We have fixed a few bad idles here on the forum in the past few months. Need to know if you are running points or electronic ignition (like Pertronix).
Also need to know if the car was running fine and has just developed this bad idle recently.

If the car is running smooth and fine except at idle that is an indication that the carburetor needs rebuilding or adjustment, or the ignition dwell and timing are off. Typically this turns out to be a carburetor issue.

Is there a fuel filter installed? What did you try adjusting on the carburetor?

The idle portion of the carburetor is a separate circuit. So you can have a car that runs well at speed but idles poorly. This can be caused by a plugged or restricted idle circuit or a bad fuel level in the bowl caused by a leaking float valve or bad float.
John

 

[jota69]

jota69,

We have fixed a few bad idles here on the forum in the past few months. Need to know if you are running points or electronic ignition (like Pertronix).
Also need to know if the car was running fine and has just developed this bad idle recently.

If the car is running smooth and fine except at idle that is an indication that the carburetor needs rebuilding or adjustment, or the ignition dwell and timing are off. Typically this turns out to be a carburetor issue.

Is there a fuel filter installed? What did you try adjusting on the carburetor?

The idle portion of the carburetor is a separate circuit. So you can have a car that runs well at speed but idles poorly. This can be caused by a plugged or restricted idle circuit or a bad fuel level in the bowl caused by a leaking float valve or bad float.
John

I'm still running the points ignition, the carburator is a progresive carburator from a fiat 850 and the car was running fine until a couple of weeks ago that it developed this idle problem. I have been adjusting the mixture screw and the idle adjustment screw but I still get the bad idle and it would sometimes cut off but besides that the car runs fine, I have a fuel filter installed between the fuel pump and the carb

 

[jjacob]

OK Fiat 850 carb.

These carburetors have an accelerator pump diaphram. So here is what I would do.
First, pull a spark plug and see what it looks like. Bright white? Black with soot?

I would suspect that if it is a carb problem that either the accelerator pump diaphram is leaking, or the fuel float has pinholes in it and is filling with fuel and not shutting off the gas supply. These are things that can occur quickly.

If the points are worn and burned and pitted, then they would need to be replaced. My suggestion is that you install the Pertronix ignition system. Cheapest place to get it is Advanced Auto Parts.


If you search for "Fiat 850 carb" on ebay you will find rebuild kits that include the accelerator pump. Mr Fiat has a very complete kit

http://www.mrfiat.com/part.php?item...Fiat850CoupeSpiderCarburetorRepairKitNew.html

but I think it is overkill unless everything on your carb is worn.

John

 

[jjacob]

On your left turn signal. Determine which bulb is not lighting up (front or back). Try cleaning the bulb and socket contacts. Next step would be to unscrew the housing from the car and clean the ground contact to the body.
John

 

[jota69]

OK Fiat 850 carb.

These carburetors have an accelerator pump diaphram. So here is what I would do.
First, pull a spark plug and see what it looks like. Bright white? Black with soot?

I would suspect that if it is a carb problem that either the accelerator pump diaphram is leaking, or the fuel float has pinholes in it and is filling with fuel and not shutting off the gas supply. These are things that can occur quickly.

If the points are worn and burned and pitted, then they would need to be replaced. My suggestion is that you install the Pertronix ignition system. Cheapest place to get it is Advanced Auto Parts.


If you search for "Fiat 850 carb" on ebay you will find rebuild kits that include the accelerator pump. Mr Fiat has a very complete kit

http://www.mrfiat.com/part.php?item...Fiat850CoupeSpiderCarburetorRepairKitNew.html

but I think it is overkill unless everything on your carb is worn.

John

The carb was rebuilt about a year ago and a new accelerator pump installed in it

 

[jota69]

On your left turn signal. Determine which bulb is not lighting up (front or back). Try cleaning the bulb and socket contacts. Next step would be to unscrew the housing from the car and clean the ground contact to the body.
John

None of the bulbs light up when I use the left turn signal

 

[Bambino]

The Fiat 850s used two different Weber carbies. The spiders and coupes used the twin barrel downdraft 30DIC type whereas the sedans used the simpler single barrel 30ICF.

I assume you have probably fitted the DIC but check which one you have as the rebuild kits are different.

Chris

 

[littlemouse]

None of the bulbs light up when I use the left turn signal

Before you get too involved in checking things, just check your earth conections are good and grounded, put the indicators on and try wiggling the earth wire at the rear of the bulb fitting and where its grounded, sometimes there is a bad connection at the spade connector to the back of the bulb unit

 

[jota69]

Fixed the turn signal problem, it was a loose connection at the fuse box.

I still have the idle problem so I guess I will be taking apart the carb and rebuilding it, if its not the carb what would be other causes for the bad idle?

 

[jjacob]

I still have the idle problem so I guess I will be taking apart the carb and rebuilding it, if its not the carb what would be other causes for the bad idle?

Valve adjustment
Point dwell
Ignition timing
Fouled spark plugs
High resistance in spark plug wires
Worn distributor
Vacuum leaks

John