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Hello and an 'it won't start' question
http://international2cvfriends.com/forum/viewtopic.php?f=7&t=2439		 Page 1 of 2
Author:  Jozza [ November 16th, 2010, 8:43 pm ]
Post subject:  Hello and an 'it won't start' question
Hello everyone,

I am now three weeks into the ownership of a 1988 2CV6 (having wanted a 2CV for many years). It's great fun but it has one 'snag' that I'm hoping you'll be able to shed some light on.

The 2CV is totally original spec-wise. 49,000 miles, original 602cc engine, standard ignition, no tuning etc.

When starting from cold it will fire up quickly on 1/2 choke, run smoothly for 2-5 seconds and then die and stop. After a bit of cranking (around 5 seconds) it will fire up, run lumpily (you have to keep the revs up with some throttle) and then 'clear its throat', often with a soft backfire or two, and run fine.

How bad the problem is depends on how long it's been since the engine was run. In the morning it starts, dies, then starts up again quite quickly. After a day at work it starts, splutters, then runs smoothly. If it's left for a few days it starts, dies and then can need a lot of cranking before starting up again.

In the cold weather today it was very reluctant to start again (once it had fired up and stopped) and until it had warmed up a little it kept dieing on the over-run.

When it's warm it runs fine - nice and smooth, does an easy (if noisy) 70 MPH and is doing around 45-47 MPG. The only other thing (possibly related?) is that when accelerating if pulls away fine only to hit a 'flat spot' in the midrange, acceleration dies away and then it suddenly picks up again- it's rather like a turbo engine coming on song. This is more noticeable when running with the choke out.

Any ideas? The car has had a new coil recently, the tappets were adjusted and the plugs and air filter changed 1,000 miles ago. I've put a ColourTune on it when it's warm and the mixture's fine, maybe a tiny bit on the rich side. The spark on both plugs is nice and strong.

I originally suspected a failed non return valve in the fuel pump and that fuel was draining away when it was sitting but I've put a new pump on it and the problem's still there. All the fuel lines and hoses seem in good condition (no leaks or splits).

Cheers in advance,

Jack
Author:  ben [ November 16th, 2010, 8:55 pm ]
Post subject:  Re: Hello and an 'it won't start' question
Too much choke? Have you tried to start it with foot down but no choke?
Author:  Jozza [ November 16th, 2010, 9:01 pm ]
Post subject:  Re: Hello and an 'it won't start' question
I have. With full choke it cranks, fires but doesn't run. With a cold engine, full throttle but no choke it just cranks with no sign of life. With a warm engine, no choke and full throttle it fires up instantly and runs fine.

Jack
Author:  ken [ November 16th, 2010, 9:34 pm ]
Post subject:  Re: Hello and an 'it won't start' question
Jozza,
if you're in the UK (ambient temperature in the mornings below 5 C?), try using full choke for the first start of the day, rather than half choke.

Edited, having noticed your latest post, seems as though the 'choke pull-off device' on your carb has gone the way of 95% of them and is now just a useless ornament.
Once the engine has started on 1/2 choke, have you tried pumping the throttle pedal if/when the engine stutters?

Might be worth checking that the choke 'strangler' is working as it should, by watching the movement of its spindle as the choke lever is operated.
There's a tiny spring which is prone to failure and if that's gone, the choke won't work as it should.

That flat spot will be cured by replacing the original 102.5 primary petrol jet with a 107.5 jet...

ken
Author:  602 [ November 16th, 2010, 9:39 pm ]
Post subject:  Re: Hello and an 'it won't start' question
Jozza wrote:
When starting from cold it will fire up quickly on 1/2 choke, run smoothly for 2-5 seconds and then die and stop. After a bit of cranking (around 5 seconds) it will fire up, run lumpily (you have to keep the revs up with some throttle) and then 'clear its throat', often with a soft backfire or two, and run fine.


Most 2cv's I have ever owned start like this in the wet winter month. My van [which is the best running 2cv I have ever had] started just like that this morning. All sounds fairly normal to me.
Author:  Sean [ November 16th, 2010, 9:51 pm ]
Post subject:  Re: Hello and an 'it won't start' question
Jozza

no mention made of codition of points and condensor or timing?

cold starts or cold damp starts?

id get new points and condenser and a decent set of HT leads

then 2-4-6-8 rule
0.2mm tappets done
0.4mm points gap
0.6mm plug gap
8* static timing(peg in hole)

and as long as there is petrol and compression it should start, and from there we should be able to tune it to run better

over rich and it will stall with choke
dodgy petrol lines it will stall under load
dodgy coil it will not start when hot

it does sound as if its a bit on the lean side with the 1st choke flatspot being so noticable
are you familiar enough with the carb to be able to locate the idle jet and the mixture screw?

finally the hand over the throat of the carb trick helps...take the rubber pipe off that goes from carb top to filter then at fastish idle place the palm of your hand over the carb untill it nearly stalls repeat a couple of times this usually clears any mild blockage in the jets

no doubt more to follow

Sean
Author:  twofifty AZU [ November 16th, 2010, 9:59 pm ]
Post subject:  Re: Hello and an 'it won't start' question
A gentleman should have a heated motor house and his car should be kept in it.

Do you have a fuel filter between the carb and the fuel pump. If it is dependent on how long ot has stood I'd wonder if ythe non return valve in the pump is doing its job.

If it drains right back it'll need to re prime itself everytime it starts. A clear fuel filter will allow you to make a visual check.
Author:  Jozza [ November 16th, 2010, 11:05 pm ]
Post subject:  Re: Hello and an 'it won't start' question
ken wrote:
seems as though the 'choke pull-off device' on your carb has gone the way of 95% of them and is now just a useless ornament.
Once the engine has started on 1/2 choke, have you tried pumping the throttle pedal if/when the engine stutters?


The choke pull-off is the little capsule on the back of the carb near the top isn't it?


Sean wrote:
over rich and it will stall with choke
dodgy petrol lines it will stall under load
dodgy coil it will not start when hot


I've never had to use full choke. It won't start from cold with the choke all the way out and if you apply more than 1/4 or 1/3 choke once it's running it splutters to a stop. It will happily run and drive without any choke after 1-2 minutes driving.

Driving under load and starting when hot are fine- it will start with just a flick of the key (or a single swing on the handle) when warmed up.

Quote:
are you familiar enough with the carb to be able to locate the idle jet and the mixture screw?


I think so. The mixture screw is on the front of the carb with an offset slot (should be under a plastic seal but that's been removed on mine) and the idle jet is under the fuel inlet to the carb??
Author:  Sean [ November 16th, 2010, 11:28 pm ]
Post subject:  Re: Hello and an 'it won't start' question
you can check the choke pull off is ok by watching what happens when you open the throttle , the wire hook affair should move , its should also be possible to pull it against resstance and it should return in when relaeased

despite often failing or falling off i quite like them saves over chokingg the engine and a boon on cars driven by the mechanically inept

make sure the points an condenser are A1

then get the car warmed and idling screw the mixture screw out till you get a nice steady tickover ajust the tickover speed to 850 rpm using the butterfly stop on the throttle mech

then screw the mixture screw in 1/2 a turn at a time untill the engine begins to falter then screw it back out by 1/2 turn

despite all sorts of crap weather up here mine will start 1st time with half choke and runs faultlessley (when the battery is up to it) poor starting means something is wrong or at least not all it should be

Sean
Author:  ken [ November 17th, 2010, 12:21 am ]
Post subject:  Re: Hello and an 'it won't start' question
Jozza,
from your earlier post, where you mentioned that with 'full choke it fires, but doesn't run', the 'choke pull-off device/anti-flooding capsule' is 99% certain to be kaput.

The thing is that with the earlier carbs, there was a strong spring on the carb which pulled the choke back to halfway as soon as you released the choke knob.

On carbs which had the 'choke pull-off' fitted, that spring was deleted, as the unit partially opened the strangler flap slightly as soon as the engine fired.

Everything works fine until the diaphragm in the unit fails, after which an attempt to use full choke usually results in the engine being 'strangled'... :roll:

ken


Jozza wrote:
I've never had to use full choke. It won't start from cold with the choke all the way out and if you apply more than 1/4 or 1/3 choke once it's running it splutters to a stop. It will happily run and drive without any choke after 1-2 minutes driving.

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