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Exhaust Popping
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12jslater



Joined: 19 Nov 2019
Posts: 4

PostPosted: Sat May 28, 2022 10:21 pm    Post subject: Exhaust Popping Reply with quote

Wondering if anyone could assist me with my for e494a running issues, I drove from Wolverhampton to Aylesbury the other weekend to visit family and the car absolutley breezed the 250mile round trip, its also my only daily car however briefly before that I had issues with the car seemingly randomly having symptoms of a blocked jet even when they were clear (dying with any throttle unless using choke). Well fast forward to this week, had the plugs out after the long drive and saw they were a nice tan colour, new plugs in (bosch) and the car ran better than previous and then not long after the car has started popping and spitting from the carb when revved cold and exhaust when revved or engine breaking even when warm but much less than cold, along with clean electrodes yet sooty on the base of the plug, checked for air leaks with gas from a blowtorch around carb, manifold to block and the manifold to manifold gasket and nothing, disconnected the vacuum wiper hose and plugged it up and no difference, engine runs worse with choke so not lean, points checked and cleaned, LT connections checked, three condensers and a spare coil tried my old dizzy cap (all known good) and all with zero difference, its driving me mad!! Hope to hear back from someone with a similar issues.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4100
Location: South Cheshire

PostPosted: Sun May 29, 2022 7:17 am    Post subject: Reply with quote

It all sounds like a lean mixture, do you have a vacuum gauge? I know you have checked for leaks with gas, but a quick vacuum test will confirm and also indicate if a timing issue.

Dave
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alastairq



Joined: 14 Oct 2016
Posts: 1950
Location: East Yorkshire

PostPosted: Sun May 29, 2022 7:38 am    Post subject: Reply with quote

Fuel tank not venting properly? [Cap?]

Fuel pump?
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Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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bjacko



Joined: 28 Oct 2013
Posts: 352
Location: Melbourne Australia

PostPosted: Sun May 29, 2022 8:18 am    Post subject: Popping Reply with quote

Maybe the timing has slipped or needs adjustment after the new plugs.
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norustplease



Joined: 11 Apr 2011
Posts: 779
Location: Lancashire

PostPosted: Sun May 29, 2022 10:02 am    Post subject: Reply with quote

I had the same symptoms with my Citroen Light 15, and got home from a long run only by running on choke.
Even stripping the carb down and cleaning it out didn't seem to fix the problem. In frustration, after months of fiddling about, I eventually changed the carb (a Solex) for an SU.
This seems to have done the trick. I have subsequently come across a whole raft of Citroen owners who have had similar experiences and eventually resorted to a carburettor change....apart from one man who fixed it by sticking the carburettor body (stripped down) in the dishwasher (when his wife was out presumably). I can only assume that there are drillings in the carb body that defy all attempts to clean them out by conventional means.
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Bitumen Boy



Joined: 26 Jan 2012
Posts: 1733
Location: Above the snow line in old Monmouthshire

PostPosted: Sun May 29, 2022 12:45 pm    Post subject: Reply with quote

norustplease wrote:
I had the same symptoms with my Citroen Light 15, and got home from a long run only by running on choke.
Even stripping the carb down and cleaning it out didn't seem to fix the problem. In frustration, after months of fiddling about, I eventually changed the carb (a Solex) for an SU.
This seems to have done the trick. I have subsequently come across a whole raft of Citroen owners who have had similar experiences and eventually resorted to a carburettor change....apart from one man who fixed it by sticking the carburettor body (stripped down) in the dishwasher (when his wife was out presumably). I can only assume that there are drillings in the carb body that defy all attempts to clean them out by conventional means.


Solex carbs are devils for this in my experience, at least using the fuels available in the last few years. My old Herald had one carb problem after another until I swapped the standard Solex for a twin SU setup. I gained a useful performance boost, slightly better fuel economy and vastly better reliability so it was win/win/win with the only downside being a little less space around that side of the engine.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4100
Location: South Cheshire

PostPosted: Sun May 29, 2022 12:45 pm    Post subject: Reply with quote

Some Zenith / Solex carbs can suffer from casting distortion over time, specifically the Emulsion block no longer sits flat to the main casting, allowing an air leak that weakens the mixture under certain conditions.

They can be fixed by grinding the carb surfaces with some wet & dry on a glass sheet.
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Ray White



Joined: 02 Dec 2014
Posts: 6286
Location: Derby

PostPosted: Sun May 29, 2022 4:43 pm    Post subject: Reply with quote

ukdave2002 wrote:
Some Zenith / Solex carbs can suffer from casting distortion over time, specifically the Emulsion block no longer sits flat to the main casting, allowing an air leak that weakens the mixture under certain conditions.

They can be fixed by grinding the carb surfaces with some wet & dry on a glass sheet.


That is my experience of them.
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