Weak Spark - Why?

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Landlover99

Active Member
Posts
282
Location
Extreme North West
Hi all,

The V8 I bought recently was becoming more reluctant to start and this morning I couldn't get it running at all. I pulled off the petrol pipe and spun 'er over and fuel positively gushed out. So I grabbed the HT coil output lead, disconnected it from the centre of the dizzy and coiled it back over itself to leave a gap of about 10mm I guess from ground. Spun 'er over again and the spark's very anaemic looking I have to say; kind of thin and yellow. What's the most likely cause of this? I'm not sure due to the fact that it's got one of those "factory set/leave alone!" dizzys which use some kind of reluctance wheel. I know where I am with cap and points but not this new fangled thing from 1989! Any suggestions?
LL
 
Hi all,

The V8 I bought recently was becoming more reluctant to start and this morning I couldn't get it running at all. I pulled off the petrol pipe and spun 'er over and fuel positively gushed out. So I grabbed the HT coil output lead, disconnected it from the centre of the dizzy and coiled it back over itself to leave a gap of about 10mm I guess from ground. Spun 'er over again and the spark's very anaemic looking I have to say; kind of thin and yellow. What's the most likely cause of this? I'm not sure due to the fact that it's got one of those "factory set/leave alone!" dizzys which use some kind of reluctance wheel. I know where I am with cap and points but not this new fangled thing from 1989! Any suggestions?
LL
Modulator on the side of the distributor can fail miserably. I had this happen once going to work. Only until an auto electrician found the problem I too was left with scratch bonce.🥴
 
"Modulator? Never heard of that! Bloody modern technology. Okay, thanks, I'll look into it. Any idea what its function is?
Its called an ignition control module, "The ignition control module is a crucial component of a vehicle's ignition system. It controls the ignition timing and spark generation, ensuring efficient combustion and optimal engine performance. It interacts with other components, such as the ignition coil and distributor, to generate sparks immediately."

So it takes the signal from the sensor and then does the biz to make the coil make a spark...... I spose!

Had one go on a Mini once. Right pain.

So it does the same as the contacts (and condenser) used to do.
 
Its called an ignition control module, "The ignition control module is a crucial component of a vehicle's ignition system. It controls the ignition timing and spark generation, ensuring efficient combustion and optimal engine performance. It interacts with other components, such as the ignition coil and distributor, to generate sparks immediately."

So it takes the signal from the sensor and then does the biz to make the coil make a spark...... I spose!

Had one go on a Mini once. Right pain.

So it does the same as the contacts (and condenser) used to do.
What he said
IMG_20250626_211750_2~2.jpg
 
What? So it's just some fancy name for an ignition amplifier? Takes the weak signal from the reluctor sensor in the dizzy and boosts it up to 12V pulses for the HT coil's input terminals? I was given to understand that the ignition amplifier (if that's what it is and it sure sounds like it) was a separate module next to the coil. But now youz are saying it's built into the actual dizzy body?
 
What? So it's just some fancy name for an ignition amplifier? Takes the weak signal from the reluctor sensor in the dizzy and boosts it up to 12V pulses for the HT coil's input terminals? I was given to understand that the ignition amplifier (if that's what it is and it sure sounds like it) was a separate module next to the coil. But now youz are saying it's built into the actual dizzy body?
IMG_20250717_164251_1~2.jpg
 
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