95 Disco 3.9 - no spark

Donno

New member
95 Disco Standard

Any thoughts on no spark from the coil?

Seemed to happen intermittently and now won't start at all and have traced it to no spark. I've done the 4 voltages at the coil and they seem good. For test 3, amplifier switching, I'm getting 12 volts with the ignition off where it says it should be zero. I seem to remember that this test was an error in Rave manual so not sure on that? Can anyone confirm proper procedure?

I have already fitted new coil and amplifier. New wires, cap and rotor. Pickup in the dizzy seems to have the correct resistance. I'm going to check the air gap and check the continuity of all the wires including the relocation wire for the amp. Anything else I can check?

Cheers
 

waveridin1959

Well-known member
I had this issue and it was the plug at the amplifier for the wires out of the pickup plate to the amplifier. The plugs contacts had worn and touching it would cut the truck off. I bent to the contacts on the male side to make a better connection. When i confirmed it I butt spliced it.

I replaced every ignition component and passed all the procedures. That connection kept the pickup plate from telling it when to fire.

Also are you sure the coil doesnt have spark when your turning the truck over? Did you hold the lead over the manifold to see if it arcs? Failed rotor button is also common.
 

Donno

New member
Thanks! So the wire from the amp to the distributor or was your amp still mounted on the distributor?

I've got the timing gun on the coil wire and not getting any spark signal from it at all.

Cheers
 

waveridin1959

Well-known member
The amplifier on my 90 was relocated to the coil. Two wires (red/blue) ran from the dizzy to the amplifier. If the amp isn't getting a signal from the pickup plate, the coil will not fire.
 

Donno

New member
Ok thanks. Checked wiring last night and all seems fine. Doesn't make sense. Will keep troubleshooting.
 

Donno

New member
Ended up being a bad rotor even though new. Put the old one back on out of desperation and she fired right up! Running great now! Serves me right for not going genuine parts.
udbMv2o.png


Thanks
 

rocky

NAS-ROW Addict
It's not just rotor arms that wear, distributor caps do to. I always replace them both at the same time.
 

waveridin1959

Well-known member
This is a trend among newer rotors. Get one of the HD versions from Lav at Series-Defender. I've had a new one leave me stranded before. The one that came on the truck lasted probably 60K miles. The new one lasted maybe 1000.

When i get a few extra dollars i'll probably switch to the DUI setup and be done with the ageing Lucas.
 

blueboy

Well-known member
The new one lasted maybe 1000.

My experience as well with Genuine. Supposedly a bad batch was made. It was very frustrating and really unsafe as the engine would just quit.

RN offers this as an alternative which is made to the old Genuine spec. Have 800 miles on it and hoping it gets past the 1k mark!

5AFD43E3-E954-4434-A7C1-5AD04532F25B.jpeg
 
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Uncle Douglas

Well-known member
Callsign: delete
My experience as well with Genuine. Supposedly a bad batch was made. It was very frustrating and really unsafe as the engine would just quit.

RN offers this as an alternative which is made to the old Genuine spec. Have 800 miles on it and hoping it gets past the 1k mark!

View attachment 8390
Had a similar experience with an OEM lucas rotor that was only weeks old.
Not sure if its the same part but we are now running these red ones from PowersparkUK. Have been very happy with their module relocation kits etc.
https://simonbbc.com/rotor-arms/lucas-35d-v8/
 
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Noyac40

Well-known member
Same thing happened to me last summer with 3 - 400 miles on it. I lost a great beach day with the kids watching my truck on the back of a flatbed. I ordered the red one from Lav based on this thread - Thanks guys!
 

blueboy

Well-known member
Powersparks makes the red rotors I linked. They also make these caps https://simonbbc.com/lucas-35d-v8-distributor-cap-powerspark-ca8-replaces-ddb107-blue/
in blue or black. Unlike the el cheapo blue caps made by others with aluminum contacts in the caps the powersparks caps utilize brass components. Quality kit. I'm having better luck with them than OEM Lucas.

Many thanks for the info.

I just checked my spare LR Genuine black cap and sure enough, it has aluminum contacts.

Their rotor looks like the one RN is selling which makes me feel even more confident in it.

Really appreciate this. Thx again.
 

rocky

NAS-ROW Addict
Depends on which version of the 35D distributor you have. I have used the 3 pins.
https://simonbbc.com/distributors/distributor-parts-spares/ignition-modules/
Pretty certain that Powerspark is the manufacturer for the kits that used to be sold by AB and others.
Have yet to buy anything from them that hasn't been an upgrade over oem.

Just spent a few mins installing the rotor/cap and wires using simonbbc. Having 8mm v 7mm wires may not sound like much but it's a big increase in cross section. That's has to help reduce current loss.
There's always a change in feel of the truck after any minor refresh like this, but it does seem peppier and smoother.
 
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waveridin1959

Well-known member
Magnacores are great wires. Ran then on my 90. I got Kingsbournes for the classic since I'm ballin on a budget.

Looking forward to finally firing up my classic this weekend.
 
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