Rough running.

[edwin]

Hi all. Got Ronnie the Renault running again with a new battery. Problem was the charger I had borrowed saying it’s full when it obviously was not. Thanks for your help.
However another issue arose yesterday. Driving along, and on half throttle it started to get a misfire. It went by driving faster in a lower gear, ie with more throttle. However when approaching a stop and changing down, with foot off the throttle momentarily, the engine immediately dies. I got home and left the car. Today started it and the same thing, only runs on half choke. Any ideas please. Thanks, as ever.

 

[André4Renaults]

I'd start by investigating the carburettor. Perhaps one of the jets has become blocked? An unorthodox method of clearing the jets, used by "old school" mechanics is to remove the air filter box and then start the engine and rev it up, then slam one's hand over the carburettor throat. The huge vacuum immediately created often "sucks" any muck from the jets, although I hasten to add this is not a "garage approved" method!

Other thoughts I've had include distributor centrifugal weights becoming stuck or, my perennial favourite, a failed condenser., although if the car does run properly, albeit on half choke, I'd suspect a fuel, as opposed to ignition, problem.

 

[Crelesy]

That's a good way to clean a carb half-assed but with normally great results. Especially when the blockage had just formed recently. I like to add that you better can use a piece of clean non splintering flatwood.
Next time your neighbours 5.7 liter V8 has the same issue with its Holly carburettor and you trying the same trick, all blood is sucked trough your skin and you can hurt your handpalm badly!
Just not to scare you, but be carefull. Engine vacuüm has a lot of power!

 

[André4Renaults]

That's a good way to clean a carb half-assed but with normally great results. Especially when the blockage had just formed recently. I like to add that you better can use a piece of clean non splintering flatwood.
Next time your neighbours 5.7 liter V8 has the same issue with its Holly carburettor and you trying the same trick, all blood is sucked trough your skin and you can hurt your handpalm badly!
Just not to scare you, but be carefull. Engine vacuüm has a lot of power!

How right you are! As I said, it was an "old school" method I learnt as an apprentice mechanic in the 1970s, when things were less stringently controlled!

Another method of cleaning a carburettor is to remove it from the car, drain any excess fuel from it and (having first ensured your wife will never use it again!) place it in a pressure cooker, together with some water & bicarbonate of soda & place it on a low heat. I've never used this method, but a friend of mine has, and both his marriage and his house survived, which was amazing in both senses, as he'd placed the pressure cooker over a gas ring. No really! He's a somewhat eccentric guy..... The carburettor worked perfectly and never gave any trouble after this!