FJ1200 not starting when all spark plug caps are connected

[Pat Conlon]

Aaah, ok got it, thanks Travis....very strange indeed....only common thread between the 2 coils is the ground.

[gpspl]

Just installed set of different coils and still the same. How to test ground?

[Sparky84]

Just installed set of different coils and still the same. How to test ground?

Was there an earthing cable under one of your coils fixing bolt?

[gpspl]

Yes, there is eyelet connector ground wire bolted to coils

If there is no spark when all sparkplugs are conected what does it mean? Load is bigger or smaller?
Why when i start engine on 3 cylinders, rev it above 2.5k and connect missing sparkplug it runs and revs to limit but dies when below 2.5k?
When i keep it below 2.5k with 3 cylinders running and just "touch" unconnected sparkplug with cap it dies imidietly like there is a short or not enough power.

What connects all those things?

[balky1]

Maybe to try running a negative wire from battery directly to coils to check if it still happens? I don't know if that is a good idea, but that should tell you the ground quality. I don't know, might be corroded on the back of the engine where it is connected and not letting through enough current for all 4 spark plugs? Does it make any sense?
Did you check how much it charges?

[Sparky84]

I have a feeling that the DCI switches the earth to coils, so it could be in the black box as you've swapped coils.

You have checked/redid earthing to rear of motor?
Everything else electrically works so earthing shouldn't be a problem.
Have you tried another battery?

[gpspl]

I tried another battery and still same.

But i have a finding, should orange and grey wires that goes to coils have continuity, even when DCI is unplugged?

Looking at wiring diagram i think it shouldn't :>, right?

[gpspl]

I tried another battery and still same.

But i have a finding, should orange and grey wires that goes to coils have continuity, even when DCI is unplugged?

Looking at wiring diagram i think it shouldn't :>, right?

I mean there is a short between orange na gray coil signal wire. I unplugged coils and DCI and it's still there. Those wires should not be shorted  right?

[Pat Conlon]

The gray wire coming off the coil is also the signal wire to your tachometer.

[gpspl]

 ok guys I fixed it.

It was a short between orange and grey coil wires where shorted. He'd to unwrap loom to find it but it's fixed. Thank you guys for all posts and help

[Pat Conlon]

Glad you found it...what was the cause of the wires shorting? Abrasion? Cracked insulation from heat?
To have a short buried a wiring loom bundle has to be the most difficult to pin point.
A common short in our FJ's is the power lead going down to the horn. The wire is hot (key on) as the horn switch simply grounds the circuit. The wire scuffs against steering neck on the frame.

Cheers

[gpspl]

It was my poor wiring job. I relocated DCI and safty relay to the rear of a bike. I haven't stacked wires when splicing and shrink tube got pinched or something and shorted both wires - i redone my wiring remembering to stack wires and just to prevent this issue again used thicker shrink tubes and "cloth" type tape just to be sure. ( I made my fj1200 a naked/streetfighter, but don't worry no working or good looking fj was harmed in the process. It was wrecked. It's a theme with all my 6 bikes as I buy wrecked unwanted bikes and fix them and customize them for my liking. It was a last bike to make now time to move to fixing cars let's say datsun 280z )

I'm planing on Makin a writeup about whole process but now I want to enjoy my bike a bit:)