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Discussion Starter · #1 ·
First I had spark and no fuel, I repaired a black and yellow wire leading to the relay, aswell as both wires leading to the fuel pump, bought a new cut off relay, now I’ve lost spark but the pump works... I’ve had big problems with the blue/yellow wire. In the diagram it looks like it only goes to three points, if I made a jumper that connects all 3 to see if it’s that wire causing the problem am I risking damage? The red on this picture is what I’m looking to try jumping, or is there a better way to check where the problem would be coming from?
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Also, the oil fan control unit is making a sparking noise? What might that be? Is it worth trying to salvage? Or am I wasting my time?
 

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Have you tried the cdi in oven trick?

instead of splicing into the harness with a red wire, why not just check continuity from cdi blk/y to spark plug, then to fuel pump relay, etc.
that way where ever you lose continuity you know you have a weak connection or bad wire.

I replaced a cdi on another 86 I had here and still showed as no spark, replaced spark plug and its been running ever since.
 

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Yes you’re risking irreparable damage to your CDI, which is no longer available. You have to be very careful. Read the manual

the blue yellow wire is the pulse generator wire and it receives small signals from the stator. check resistance values for the pulse generator (Bu/Y) and the exciter coil (black/red) by using the green/white wire.
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When you switch on, you should have a steady neutral light and the Oil light should come on momentarily and then go out.
 

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Discussion Starter · #5 ·
When you switch on, you should have a steady neutral light and the Oil light should come on momentarily and then go out.
Have you tried the cdi in oven trick?

instead of splicing into the harness with a red wire, why not just check continuity from cdi blk/y to spark plug, then to fuel pump relay, etc.
that way where ever you lose continuity you know you have a weak connection or bad wire.

I replaced a cdi on another 86 I had here and still showed as no spark, replaced spark plug and its been running ever since.
power doesn’t make it to the spark plug, it gets power at the relay but doesn’t make it up to the spark plug or the CDI, there’s also a black/brown wire that also only makes power up to the relay, aswell as the cooling fan control unit seems to be making a clicking or zapping sort of noise and I’m not sure if that’s normal, but when it does make the noise the oil temp light stays on and when it doesn’t make the noise the light stays off
 

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Okay that make sense now. Perform the engine oil overheating diagnostics.
The fan control unit is under the left inner fender well. The oil temp sensor is behind a panel which is behind the right footpeg.
Inspect and test the wiring and sensor for shorts.

if the FCU is clicking on and off then you need to find the wire break or short.
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