Merc 4.3 No Spark

[300sflyer]

I have just reassembled a 1990 Merc 4.3 V6 with a thunderbolt 4 ignition system, after an issue with a cracked block.

I have the engine sitting on a skid, and am trying to fire it up, but she won't start. My battery and starter are just fine as the engine turns over as it should. I have put a wire directly to the + side of the coil, [+12V directly from the battery] and am jumping the starter with a screw driver. A bit crude I know, but it has worked for me in the past.

I used these same ignition components a few weeks ago, and it ran just fine. [except for the cracked block] The distributor is installed correctly, [rotor pointing at #1 cylinder, with the crank at 0 degrees on compression stroke] and all of my wiring is in good condition. As I said it ran just fine a few weeks ago. For some strange reason, I am not getting any spark at the plugs now.

Thanks for your help!

 

[Fun Times]

Re: Merc 4.3 No Spark

For some strange reason, I am not getting any spark at the plugs now.

Thanks for your help!

Are you getting spark out of the coil?

 

[Don S]

Re: Merc 4.3 No Spark

 

[300sflyer]

Re: Merc 4.3 No Spark

That helps... Thanks.

I have 12V at the + terminal on the coil, and at the red/white wire on the distributor. Using a spark plug and lead right off of the coil itself, and touching the two green/white wires together, I have spark from the coil, as the spark plug was sparking. Next was to replace the sensor in the distributor, and I did so with what is believed to be a known good one. Then I tried to fire up the engine, and still no spark at the plugs. I have swapped caps and wires, and it also made no difference.

I'm stumped... Any other suggestions?

Thanks

 

[300sflyer]

Re: Merc 4.3 No Spark

Update... I disconnected the ignition interrupter switch, and she fired right up. I assume there is a problem with this switch?

 

[timothy2222]

Re: Merc 4.3 No Spark

Unplug the green/white wire from your dizzy then check.