Ignition control unit (ICU) failure symptoms?

An alchemy of sparks, copper wire and earth

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matteo
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Ignition control unit (ICU) failure symptoms?

Post by matteo »

Yesterday I had my engine (CU 2ltr a/c) starting and running fine. In the evening I had the spark plugs out as I was checking compressions (with the hall sender plug disconnected as recommended in Autodata manual) and subsequently checked sparks at plugs (with hall sender plug reconnected). Sparks were in good condition at all plugs.
Now the engine will start OK but after 2 seconds cuts out <SIGH>

Have I managed to wreck the ignition control unit (ICU) and/or hall sender do you think?
I've looked back in previous threads for example http://archive.club8090.co.uk/viewtopic ... 3#p7750093
and it seems that because I have sparks is less likely to be the sender? So I'm thinking I need a replacement ICU?

Any pointers or similar experiences welcome.
1980 2l CU Aircooled; left-hand drive - now officially a historic vehicle!

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937carrera
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Re: Ignition control unit (ICU) failure symptoms?

Post by 937carrera »

Are the anti dieseling / cut off valves on the carbs working correctly, vac lines to the dizzy still connected correctly. ?
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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matteo
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Re: Ignition control unit (ICU) failure symptoms?

Post by matteo »

Hi,
Yes the vac lines all secure and in place.

As far as I know the cut-off valves are working OK as previously (i.e last weekend) the engine would run and when either of the cut-off valves were pulled the idle revs would drop right down. As the engine won't run now I can't do the same check. Perhaps I could check resistance across the valve?
1980 2l CU Aircooled; left-hand drive - now officially a historic vehicle!

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937carrera
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Re: Ignition control unit (ICU) failure symptoms?

Post by 937carrera »

Ignition on, disconnect / connect the electrical connection. You should hear / feel it click. Don't allow the spade to go to earth

Stopping after a couple of seconds seems more like fuel running out / idle jet blocked rather than ignition module as the van starts so well. Against that I'm assuming you are on twin solexes, so unlikely for both to fail at the same time. Does it just stop, or cough / splutter as though one side only is trying to run.

Have you made sure that the connection to the balance pipe across the carbs is still in place and the rubber is not perished. Non idling is actually a classic sign of an air leak there, had it three times on my 412ls

Will it run at a fast idle, using the accelerator pedal ?
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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matteo
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Re: Ignition control unit (ICU) failure symptoms?

Post by matteo »

Thanks Carrera - I went back to the engine over lunch break and whilst all the vacuum lines were in place the lower rubber pipe from the left carb to the central idling circuit was off. I must have dislodged it whilst wrestling to the get the compression tester into #3. Oh dear I feel like a right spanner! :oops: Thanks for the suggestion to check :)
1980 2l CU Aircooled; left-hand drive - now officially a historic vehicle!

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937carrera
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Re: Ignition control unit (ICU) failure symptoms?

Post by 937carrera »

:ok

Glad you got it sorted, that balance pipe issue is common and I'm always a bit slow at remembering the solution :lol:
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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