440SI Ignition Capacitor/Condenser – Weak Spark

[Brooklyn440]

Our 440 is cranking over but failing to start. This is a progressive problem, which has got worse over time. Initially by cranking over the engine and depressing the accelerator it would start, but at times ran roughly. The engine is as follows:

• Fenix 3 computer/engine management
• B18U engine, 1.8 litre single point injection 200/203

Using an in-line spark plug tester there seems to be a weak spark. I have replaced the ignition control unit including base unit and primary/secondary coils. I have also changed the ignition leads, the flywheel position sensor and the spark plugs. I have a new distributor cap and rotor arm on order.
When changing out the ignition unit I discovered at the bottom of it the black capacitor/condenser shown in the attached photograph.


The following is written on this capacitor:
FACON
220μF
DC 2635F9V
16V
Made in France

I am somewhat surprised that this capacitor is present since with electronic ignition I thought there was no longer a need for a capacitor/condenser to prevent contact breaker points arcing and becoming damaged. However, since this capacitor is present I assume it has a useful purpose -does anyone know what the function is for this capacitor ? Potentially it might help boost the spark and since I know that capacitors tend to deteriorate over time, I was thinking to replace it. However, finding a 220μF ignition capacitor is proving to be difficult.

An Intermotor condenser 35130 seems to have been used on the 240 and 240 but this capacitor seems only to have capacitance of 0,25 µF which is much lower. Hence any advice on where to buy a suitable 220μF ignition capacitor would be much appreciated ?
If anyone from the symptoms described above can make suggestions as to what the fault might be that would be much appreciated. I have interrogated the diagnostic unit and for position 2 returned a no fault 1 1 1. I am not sure if fault codes would appear if the car does not start – can anyone advise ?
Many thanks,
Martin

[dcw]

I can't tell you the exact function the capacitor carries out but I can confirm it is a standard part of the ignition unit set-up.

I have a spare one here you'd be welcome to try if you like - it is part of what, as far as I know, is a fully working ignition unit.

If there was a fault in the ignition system I would expect it to throw up an error code on port 2 of the diagnostics. My first thoughts on that front were the flywheel sensor, which I note you have changed, and the MAP sensor - that is assuming the B18U has one; sorry, it isn't one of the engines that I know!!.

Thinking in terms of eliminating the obvious - and in no way wishing to be rude or imply you are silly or anything, but I know myself how easy it can be to overlook the simple things - what state is your battery in? Also, is your air filter clean and not clogged? You say this appears to be a problem that is gradually getting worse, and hence a failing battery came to mind. Have you put a voltmeter across it and checked its charging rate etc?

If you'd like to try the capacitor though just drop me a PM with your address and I'll send it up to you. Won't cost you anything so might at least be worth a try?

All the best

David

[Brooklyn440]

Hi David,
It is extremely kind of you to offer to post me a capacitor. If no one can advise a part number/specification for a modern replacement capacitor I will take you up on your offer. In general, I hope these capacitors are still available or else I guess we will all have a problem in a few years’ time.

The battery is fairly new and I have kept it charged up when for the various attempts I have made to get the car running. Since it is cold at the moment I plan to try with another battery and jump leads at my next attempt. I have a new air filter and will install this when I try again when hopefully I will have received a new rotor arm and distributor cap.

I am also thinking of trying spraying some Easystart into the air intake to try and check whether or not fuel supply could be an issue. When I turn on the ignition, I can hear the fuel pump prime for 30 seconds, but I guess this is not conclusive proof of fuel delivery.

Best regards, Martin

[dcw]

Good luck Martin - it sounds as if you are gradually working through all the possibilities.

Keep us posted, and just let me know if you want to try the capacitor.

I'm afraid your comments about availability are all too true, as with the ever dwindling supply of 400 series spares in general...

David

[Laird Scooby]

That capacitor is almost certainly to prevent radio interference but i'm more confused by the fact the earth connection appears to be loose? Presumably because you were dismantling things. Can you see where the cap was meant to be connected?

I'd suggest you try the Easy Start as you're considering, if it fires the next thing i would consider is condensation in the fuel tank. The symptoms you've described so far fit with that.
If it fires with Easy Start, invest in some meths. If your fuel level is 1/4 tank or below invest in :

https://www.toolstation.com/methylated-spirit/p99550

Add it all to the tank and take it for a drive (use Easy Start to get it running to start with) to circulate it through the system and remove the condensation. Inline spark testers don't always give a good impression of the strength of the spark, the fact you've had a progressively worsening situation also suggests condensation in the tank.

Good luck and let us know how you get on.

[Brooklyn440]

Many thanks Laird for these suggestions.

The earth connection was loose, since I had removed the ignition unit.

I have now tried Easy Start squirting into the black plastic opening created by removing the air cleaner hose (picture attached) while cranking the engine and slowly pressing the accelerator. The engine did not fire at all despite repeating this process three times. In the picture you can see that some of the Easy Start formed a liquid and then dripped out of the black plastic opening. Hopefully it will not have damaged the new ignition leads!

My assumption now is that either a dodgy rotor arm or distributor cap is resulting in too weak a voltage pulse to create a spark at the spark plug terminals. Hopefully when I receive the new rotor arm and distributor cap this will get the engine running. If not, I am a little stumped, fuel, correctly timed spark and compression should result in a running engine.

Cheers,

Martin