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