trace the blue with orange wire make sure there is 12V on it and that it has continuity to the ecm from the coil

 

Paulmedford, I think it’s the ecm too.
when should that wire have voltage on it?
Only when it’s cranking?
How much voltage do I expect? 12v?

 

it should have 12V when cranking then drop way below12 as the the ecm grounds it to spark

 

but you must check continuity from the coil to the ecm. Sometimes the wire breaks and the ecm can't fire that coil

 

are you getting the trigger signal from the ecm to the coil? it is a ground,,,,the ecm grounds the coil and it fires,,,,,,look up how to do that test with a 12 volt test light.
m

 

Ohm the coil.. Primary should be about 0.5 ohms. Primary might be shorted. If you messed with the coil, check the pins.

 

Set to AC? Should be 12V DC most of the time as stated above.

Add:

Motor has to be running or it's only on for a few seconds at key / srun-stop switch on. While fuel pump running.

 

Can you be specific in how to do that please

 

I can’t find anything on how to test this.
I’m getting a bit confused atm.

With the ignition on, the blue with orange wire (front cylinder) and the yellow with blue wire (rear cylinder) are both earthed while testing with test light. (Clamp is on positive battery terminal)
While running if I probe the rear cylinder wire it will kill the engine, if I probe the front cylinder wire nothing changes, but that cylinder isn’t running in the first place. This is with the test light clamp on positive terminal.

While running if I probe those same 2 wires with the clamp on negative battery terminal I get a positive light on the test light.

 

It has 12v on it as soon as ignition and run switch are on until the fuel pump stops. Then has 12v again while cranking and then running.
The rear cylinder wire does the same, the only difference between the 2 is that the rear cylinder shows a shakey light on the test light globe where as the front cylinder wire shows solid light on the globe.