Citroen DS23ie 1974- engine not starting when warm

Greetings all

My name is Warren and I live in Gold Coast, Australia. Cars include a Citroen DS23ie and Citroen SM 3.0l carby

I have an unusual problem with the DS. It has all the original D Jet injection. Only change is a 123 distributor with electronic triggers for the injection

When cold (say 24-26 degrees C here) it will start and run fine all day long. However if it is switched off and left, say, 5 minutes it will crank but not start. Leave it to cool down +/- 3 hours and it starts and runs fine again

I have checked fuel pressure, spark etc and replaced the coil, HT leads, spark plugs, fuel filter. Adjusted valves. Injectors were replaced 2 years ago

I have tried swapping out the ECU and pressure sensor but no difference. Also no difference if I disconnect the cold start injector and thermos time switch. Disconnecting the wires to the thermal sensor TS2 causes the engine to run very rich

My local Bosch Euro service centre has not been able to help at this stage

If any of the experts have suggestions on possible causes of the problem, I would be very appreciative

Thank you

Warren

Hi Warren,

thanks for opening a new thread.

When your enginge won't start, how do your spark plugs look like and do you have a strong spark?

Hello

Yes spark is good. I checked by connecting a lead with a spare plug set at double normal gap, and all is good. Also checked all plug leads and coil lead with an induction timing light and all are working fine

Hi Warren,

when your engine does not start, how do spark plugs look like? Wet, black, white ?

Hi Warren and Welcome to the forum,
when I read in German forums gas bubbles are a great problem at the carburator-equipped DS.
I read the engine compartment gets very hot and the fuel transport can break down totally in high temperature conditions.

D-Jet-cars shouldn't have this problem because the fuel system bleeds automatically.

But - the system needs a running fuel pump to do this.

Please check: Is the fuel pump running all the time while you are cranking or only for one or two seconds when you switch on the ignition?

Regards
Norbert

Thanks for your suggestions
As an experiment I have tried wiring the fuel pump so that it stays on constantly- no change
The spark plugs are wet and a bit black when the engine cranks
However the hot starting problem persists intermittently
After a run with engine hot; switch off; wait one minute- it will crank but not start. Let it cool down for 2-3 hours and it starts fine
A strange intermittent problem. Any other suggestions?
Thanks
Warren

Hi Warren,

wet spark plugs indicate a problem with ignition. If it was only 1 or 2 cylinders it could also be leaking injectors. But if engine wont start at all, all4 should leak,

Hi Warren,
fine you already tested the fuel-pump-problem.
If you had written before the spark plugs are dark and wet, I wouldn't have suspected this problem.
As Volker wrote: ignition or injectors are my favorites, too
You told us you replaced them 2 years ago. By original Bosch injectors or another brand?
Please check the fuel pressure. It has to stay almost constant after you turned off the engine. Maybe leaky injectors o cold start valve flood the engine when you turn it off.

The 1-2-3 isn't fault-free. I think you or your Bosch service have to check the ignition in the faulty condition using an oscilloscope in the case the fuel pressure is o.k.

Regards

DS23ie schrieb: ....
The spark plugs are wet and a bit black when the engine cranks
...
After a run with engine hot; switch off; wait one minute- it will crank but not start. Let it cool down for 2-3 hours and it starts fine
A strange intermittent problem. Any other suggestions?
Thanks
Warren

Hi Warren,

do you have an second fan for cooling? Is it still running after shut down?

Try the following: press the accelerator of full and hold this position, before and until you crank/start. After 10 - 20 s the engine will run.
Had the same Problem last Summer, when we have here more than 35 degrees.

If it doesn't work, better use the boat ...

Best regards
Hans

Great suggestions, thank you
I will re-check fuel pressure and swap back the original Bosch distributor instead of the 123
Injectors are correct Bosch replacements and have worked fine for 2 years
Electric second fan is powered off the ignition coil so only works with engine running. Maybe in short term I'll leave ignition on to keep it running
And if none of these work- I'll use the boat!

DS23ie schrieb: ...Maybe in short term I'll leave ignition on to keep it running
...

Don't do this... this kills the coil and / or the 1-2-3.

Regards
Norbert

Hi Norbert,

he wants to keep the car running - that will not destroy ignition coil or distributor. That's what they are made for. And even letting ignition on while not running the engine should disconnect ignition coil.

Hi Volker,
the 'keep it running' can be related to the fan as well as to the engine...

Regards
Norbert

Hi Norbert,

but the 123 ignition has one advantage: It will switch off current through coil with resting engine 1 secoand after engine stalls.

Hi Volker,
thank you for the information - I didn't know this.
The Pertronix (maybe only the cheaper / older versions) doesn't have this feature.

Regards
Norbert

Hi Norbert,

Pertronix earlier had specs on the Internet where they described which Ignitor version can drive which current and which version can switch off current on stalling engine. Earler stalling switch-off out of my memory was only available on Ignitor 3 (which caused other problems).

Warren, I own a DS-21 IE. I had exactly the same problem going on. An experienced mechanic threw out the 1-2-3. It has weak spark, and under pressure (compression), even more so. I exchanged it with the original part and all problems were gone. I know the 1-2-3 system os very tempting, but you are not the first one, who is experiencing this kind og behaviour. For my SM, they do not even sell the 1-2-3 anymore... Just saying...

Best regards Irmin

Thanks to you all, the problem is solved
Irmin has correctly identified the issue- the 1-2-3 distributor. Gold star!
I re-installed the original Bosch points distributor and there is now no problem starting from hot. The engine also has much more power. Among its other faults, the 1-2-3 was causing cylinders 2 and 4 to run very lean as the spark plugs were white after a run.
Thank you all again. A great forum
Best regards, Warren

Hi Warren,

I have always warned people that such a higly elctronzed ignition distributor causes its own problems over time. I was often criticized for trying to stop people from upgrading to a modern solution. Her is the proof that I was not completely wrong.

Thanks for your feedback, Irmin and Warren

For the Citroen Sm- the scene knows, that the 123 does not like the heat in Citroen engine compartments.
I think, a better solution was a Lumenition ignition, fitted in the original distributor.

Andreas