Zenith 28iF

[NickHay]

I've already posted about a possible air leak but my running issue isn't that. So my car starts but dies after a short time, I can only assume that it's when the float bowl empties. I've thoroughly cleaned the carb as in taken it apart and cleaned the jets etc, the pump is working, the filter is okay, I took the pipe off the inlet and fuel pumps through on starting. The needle valve is also 'roughly' at the correct measurement and I've tried starting without the fuel cap on just in case of negative pressure but still the same issue. The car will start okay but will stop after a short time.
I have no idea what to try next, so frustrating. Can anyone help please?

 

[JdeW]

When the engine dies, open the top of the carburetor and check weither the fuel bowl is full or empty.
When it's empty, check the correct operation of the needle valve, maybe the needle keeps hanging due to a too high fuel level.
When it's full the ignition coil could be a cause

Maybe still some airleak at the base of the carb.
Get a really flat surface (thick glass plate) a sheet of sandpaper 400 then 800, and flatten the carb foot in figure 8 movement.

 

[NickHay]

Thank you for your reply. I'm confused a little with regard to the needle valve when you say.....

maybe the needle keeps hanging due to a too high fuel level.

so the needle hangs down in its extended position when the float is empty and then will rise and shut off supply when its full? What do you mean when you say keeps hanging? I also checked the bowl when it dies and it is indeed empty. I just don't understand what could be causing this, everything seems to be operating as it should in order for the engine to run, so annoying! I should also add that I have now tried 2 carbs but the same issue with both.

 

[NickHay]

Not sure whether this will have a bearing but I've just noticed that the breather pipe is not in the top hole of the tank, it's come out. Surely this can't be the issue?

 

[JdeW]

Thank you for your reply. I'm confused a little with regard to the needle valve when you say.....

so the needle hangs down in its extended position when the float is empty and then will rise and shut off supply when its full?

When the bowl is emtpy, the float is down and the needle valve is open and fuel runs into the bowl causing the float to rise. When the bowl is full the float presses the needle valve and closes the supply.
It is very likely that the needle valve gets stuck in its closed position, so no more fuel supply, the bowl runs dry and the engine dies.
Maybe this helps https://www.renault4.co.uk/forum/threads/zenith-28if-problem-solving.8248/