Technical Idle stall issue diagnostic

[pepita]

Hello fellow forum members and happy new year!

A bit of background on this one: I set off from Paris to Zurich and on to the Austrian and then Swiss alps with my 1988 Panda 4x4 Sisley between Christmas to today. She performed really well despite very cold weather in the first half of the trip. In the last few days however, she has started to stall on idle even when the engine is most definitely warm. The only way to save it is to pull the choke out slightly before coming to a stop or to rev it continuously.
It is not particularly cold now (between 3 and 6 degrees) although I am at 1,800m in altitude, it was also behaving the same way at 1,200m – so my suspicion is that it is not altitude related.
The car seems to run fine while under way.

I have done some research on the forum and compiled a list which I have tried to sort in order of intervention difficulty:

Order	Item	Question
1	Check distributor cap	What should I check for here exactly?
2	Idle speed	Increasing the idle speed would probably fix this but would I just be hiding another underlying problem?
3	Spark plugs
4	Ignition timing and the points gap	How?
5	Fuel pump
6	Check that there are no air leaks and air filter is clean	How does one check for leaks?
7	Vacuum advance unit or a condenser breaking down

I would be very grateful for your view on the items on this list or if there is anything else that could be an obvious culprit.

Thank you.

 

[Dragon Man]

hmm you can rule out 2 on the list, the 4x4 does not have points or a condenser, it uses an electronic points system which sits on the back of the distributor.
this thing is prone to overheating/failure, well worth moving it from the distributor and just letting it hang on a zip tie so its not touching a hot engine.

vacuum leak is a possibility, maybe a pipe has chafed through worth checking. the vacuum advance is easy to test to see if it still works, just undo the pipe from the back of the carb and suck on it. if you can pull a vacuum on it the diaphragm is fine, but do check to see if it does move as it may have somehow seized up. just pop the distributor cap, rotor arm, and splash guard off and see if things inside move when you suck on the pipe.
worth noting that theres another small pipe on the back of the carb that goes to a smaller vacuum actuator which controls the choke. this small pipe has been split on 3 carbs so far i have come across.

its possible it could be a fuel pump or blocked filter issue.. only getting enough fuel when revved as its a cam shaft driven fuel pump.

it could also be a float level issue in the carb its self.

start with the easy stuff first.

hope this helps!

 

[pepita]

Thanks @Dragon Man, super helpful. I will update my checklist and start to work through it.

What do you think about the idle circuit fuel cut off solenoid being the culprit? Should I add this to the list as well?
Would you happen to have a picture of this? Of course I forgot my Hayne's at the starting line.

 

[pepita]

Found it! And lo and behold, the spade connector had come loose! Panda has a stable idle again.
I've re-printed the list below as a resource to others:

Item
Check distributor cap
Idle speed adjustment
Spark plugs faulty or worn
Idle circuit cut-off solenoid: Wired and working?
Fuel pump or blocked fuel filter
No air leaks and air filter is clean
Vacuum advance unit broken

 

[Dragon Man]

ha yes i knew i forgot something! you know i have seen those fuel cut off solenoids on other things, got me wondering if it would be possible to replace the on on the panda with another one with a more powerful spring so that no fuel gets past it. make a good security thing if it was on a hidden switch.
i need to find out what thread and plunger size / reach they are..