Won't fire up.

[fausTVR]

Never had this before but I knew it had to come one day. I'm no auto electrician but have a very basic understanding of things generally.

It turns over fine, fuel pump priming but doesn't even cough. Checked for spark using king lead and zilch. I thought immobilizer perhaps.
I swapped the two similar relays over which hang off loose wires, I think these are fuel pump and ignition? That changed nothing.
There is fuel pressure in the rail which I checked via the valve thingy and it squirted.
There is voltage in the low tension supply to the coil with ignition on (not when off) but does this rule out immobilizer cutting ignition? I notice that there is a pair of LT +/- wires from the ignition amp and a second pair from the loom going to the coil. I'm assuming that since this supply is live with ignition on, the immob' isn't interferring?

any thoughts?

The car is stranded downhill from my garage from last week, when I shifted it out to make way for tree felling. I'd dearly like to put it back away.

[Colin RedGriff]

If there's no spark I would look at the coil or the ignition amp.

[s p a c e m a n]

IIRC the standard immobiliser is just on two circuits, the starter and fuel pump so it's unlikely to be anything to do with that if it's original. +1 on coil etc.

[fausTVR]

Thanks guys so far. I did try a random coil that's kicking around from God knows what, but no dice yet.

With much grunting and a neighbour's help we managed to inch it back up into the garage safe and sound at least. I thought these cars were meant to be light!

The last use the car had last year, on empty roads, it was stuttering above 4k revs and I'd put it down to the 97 fuel I'd had to feed it that day (always 99) but could that have been coil going? It has started ok twice this year.

Edited by fausTVR on Sunday 13th April 18:51

[QBee]

My 500 ran very happily yesterday on 97, will even run ok on 95. No, it's not that. The ECU adapts for the grade of fuel.

Sounds like coil or ignition amp to me. It's not immobiliser in my limited experience, as you wouldn't get the fuel pump priming. Could be a cracked dizzy cap or grotted up rotor arm.

[fausTVR]

I think you're right about poss coil/ amp QBEE, but I'm sure they don't allow for fuel grade via ECU as there are no knock sensors on these old buses. My thinking was with the misfire that my advance is wound up quite far and is only happy with 99 these days because of it.

I've never had coil trouble before so a bit new to me.

[QBee]

Nor have I had spark problems so far - my only non-starting has been failed battery and failed immobiliser. Sorry, it's not fuel grade - it would run, just badly.

You said it yourself, no spark. Turns over fine, so not immobiliser or battery/alternator. So must be the HT side. Either your 'king lead has failed, or your coil or ignition amplifier.

Or, logically, whatever lead supplies the coil with juice. Check connections before changing components.

[s p a c e m a n]

Seeing as you've tried another coil, did you use the same king lead? Just thinking outside the box

[fausTVR]

Thanks for the thoughts chaps. Looks like it's narrowed down to king lead / coil / amp then which is a relief I suppose, didn't much fancy tackling the immobilizer.

[Dr Mike Oxgreen]

Stuttering above 4k rpm was precisely the first symptom when my coil failed in France a year or two ago. But it could also be the amplifier module.

[gruffalo]

from experience the coils fail more often than the ignition amp, it would be my first place to spend time looking.