Auto choke and poor sparks

[cacaolat]

it happened again. Last night the good old Bx was driven just about a mile. parked it, and a few hours later it would not start again.
It happened before and I got some advice , but I still did not know how to manually move the choke flap. Had to call the Recovery again. Was told that the auto choke did not work and that there was no spark. But it worked again after the helpful guy moved the choke flap manually.
Any advice. Maybe I should a garage to have a look at the electric poor spark issue. How can I improve the choke. Is converting to manual choke the only answer ?
everything else works and just this occasional non starting lets the car down

[jeremy]

The choke is probably either sticky mechanism or a failed operating capsule. If its intermittent then it may be sticking - you can see it if you remove the air inlet hose from the carburettor. Its probably 2 flaps as its a twin choke carb - and when its cold they should shut and slowly open as the thing warms up.

Start the engine with the hose off and let it warm up and see what happens

Loads of info here - see READ ME for directions.

http://www.rwbsmith.plus.com/citroen2/

There are many causes of poor sparks - first thing I'd do would be a visual inspection of all components and their connections than I'd meter the leads for resistance (which should be below about 15,000 - 20,000 ohms). I'd then remove the distributor cap and make sure all was well there and if I'd found nothing yet I'd look at the coil pack with a view to changing it.

[mnde]

Hi Gregor,

I need to follow up on my promise to come and look at your car sometime! I used to have exactly these problems with short journeys, or trying to restart after stalling when cold.

One way of making the choke flap move is to floor the accelerator, *then* operate the starter. You will see that if you open the accelerator fully, the flap will open a pre-determined amount; AFAIK this is part of the deflooding mechanism. In the past, this was the only way I could get my car to start, save removing the gubbins from the top of the carb and inserting a screwdriver to keep the flap open.

I think the reason for no spark is that you will have flooded the engine while trying and trying to start the car.

Good luck!

Mark.

[cacaolat]

Sorry the late reply I was abroad.
Thank you Mark, I was wondering why there was no spark and later there is enough of spark again.
Sorry to hear about the breakdown you have experienced with your meteor.

[cacaolat]

The reason why I was always worried to fully down the accelerator is, because I wanted to avoid flooding it. But thanks for the advice I will try this. although I did not do any repairs to is it, the car always starts first time now....
Mark let me know when you are in the area, just to have a look with your experienced eye. I know that at the moment you are busy with your own cars...

[mnde]

Okay will do. My BX is still "en pannes" at the moment, but the GSA is (touch wood) running like a sewing machine at the moment.

Mark.

[cacaolat]

just wanted to return from a local restaurant (should have walked) and say to my wife, how nice the car is working these days....then the same thing as above happend again..... the car had only been driven for half a mile... after it would not start...I remembered some of Mark's (mmde) words....fully press the accelerator....no luck as I did not remember the sequence...first pressing...then ignition...
just came home to check that and hopefully the car will start in an hour again....

[AndersDK]

The autochoke suffers from wear & tear and must be re-adjusted now & then on the waxstat cylinder setting.
A general overhaul will do it very good as the choke strangler flap also has a tendency to stick - in strangled position - flooding the engine.

http://www.rwbsmith.plus.com/citroen2/Carburation/
- covers just about any thinkable BX carb type.

Another - entirely different - problem may kick in its nasty effects : a defective ignition module. They usually starts to get temperature sensitive for a while, and then suddenly no warning lay off for good.
2 types are around for the BX :
the 7pole variant fitted next to the coil on the firewall.
or the 5 (3+2) pole variant fitted to the dizzy body.
Both types are used in many other car makes & models and are available at low cost as aftermarket parts (£20-ish).
No need to be a specific make or subtype.

[cacaolat]

Just got back...I returned to the car with a screwdriver and torch. Keeping the choke flap open did not help. I had to call the recovery again (the 4th time in a year). At first I was worried by the speed the lady from the recovery truck was pulling out pipes and roughly handling the stuff. but then the car started, she suspects the ignition module, or even only the plug that goes into it....maybe it just needed a wiggle. It is a blue ignition module, I think it is from Bosch but I will have a closer lock tomorrow in daylight.

[cacaolat]

Next Day: of course the car started without problems today...I am still confused wether it is the carburator or the ignition module or just the plug to the module. The ugly old air pipe is sort of pushing the plug a bit....see photo.

[jeremy]

For the BX 19 (which I think is similar)Citroen recommend foot off starting when cold - which means the auto-choke is self setting (Some Fords had to be set by depressing the accelerator). For hot starting they suggest pressing the pedal slowly to the floor then operating the starter. If it won't start and flooding is suspected - depress the pedal to the floor and keep it there then after 10 seconds operate the starter.

These carburettors have an automatic choke which provides the richer mixture needed for cold starting.

The carburettor has an accelerator pump for both chokes and this is operated by the throttle pedal - so when the pedal is depressed 2 jets of neat petrol are pumped down the engine inlet. Keep pressing the pedal - pumps more fuel in - and eventually the engine floods and won't start.

A flooded engine will often fire if its scavenged - which means holding the pedal hard down and cranking the engine. The engine should draw in air which dilutes the fuel until eventually combustion can take place. This is not assisted by an auto choke flap being shut.

Even if your engine doesn't run I think I'd have expected some form of firing if it was a fuel problem so my suspicions would be directed to the electrics - which means amplifier, coil, leads and connections.

Any possibility the ignition key switch itself is defective - any signs of malfunction , reluctance for bits of electric kit to work etc? (Had one go on ZX - wouldn't operate starter to begin with - then it started cutting out when the brakes were applied and the key ring swung around!)

[mnde]

Where are you Gregor? London's a bit vague I'm free on Sunday at the moment if you are. You don't have a jack do you? I'm desperate to get my new accumulator sphere fitted!

Mark.

[cacaolat]

Mark, I am in Camberwell SE5, i am free on sunday and could meet you wherever is convenient for you. I only have the original jack that comes with the car, unfortunately.

[Way2go]

Standard BX jack is good for the job along with a pair of axle stands. Suspension on high. Jack each side and place axle stand under front reinforced sill point with opposite rear wheel chocked. When car is up on stands (mid holes are enough) with both rear wheels chocked, move suspension to low & car will settle at back and then you can release bleed screw.
Chisel positioned at angle to sphere weld & hit with hammer is usually enough to be able to unscrew sphere and fit new hand tight. ( Not a lot of room there to use other tools )
When jobs done raise suspension back to high on engine before jacking and removing stands

[ellevie]

Why not simply remove the plug from the amplifier, apply some WD40 to its contacts, and then push the plug on and off 2 or 3 times to clean the contacts. It looks like the lady may very well have found your problem. I had a cold start refusal which I traced to the amplifier plug, and another member (doz) recently reported a misfire problem which he cured by cleaning this connector. http://bxclub.co.uk/forum/viewtopic.php?t=6873

I don’t think it’s very likely that your autochoke is the problem. The autochoke performs several functions, but the particular malfunction which could cause cold start refusal is very easy to check. The choke flap is the one which stands straight up when the engine is fully warmed up. With the engine cold, you should check that it is fully down in the completely closed position. You should now be able to push it with your finger into the full upright position. It should feel reasonably free and when you remove your finger the flap should spring back to the fully closed position. If for some reason it does not fully close, then this could cause cold start refusal.

Solex carburettor in my BX19TRS



As a matter of interest, if you had bought the spark tester that I recommended in your earlier thread, you might have been able to use it to easily verify if the fault was caused by spark failure. When the engine refused to fire, you would simply pull off one of the plug leads, pop the tester over the plug, and plug the lead on to the top of the tester, and then try starting again. If the tester does not “flash” , then you would know that there was no spark and then you would not need to speculate about the autochoke. It only costs £2.89 inclusive of postage. http://cgi.ebay.co.uk/The-Legendary-Ora ... dZViewItem
You can see the orange spark tester in use in the bottom left corner of the picture above.