454 no spark

[matthewwhite]

I have a 454 engine with no spark.
replaced the coil distributor cap, rotor arm and leads. still no spark. the grey wire that comes off the coil that goes to the loom, does anyone know where that goes. I have tried a continuity test on the plug it goes up to an I have continuity on every pin from that grey wire so believe there is a short. any help would be great
thanks

 

[Scott Danforth]

welcome

grey wire is tach

what year or serial number is your motor

 

[Scott06]

Do you have 12 v on positive side of coil when key is in run? Are you getting spark off coil and loosing it in the distributor ?

Check the man overboard switch - ,make sure it is securely in on position.

 

[tpenfield]

I had a 454 with no spark. It was the gen 6 version, MPI, with the VST distributor. I replaced the distributor - problem solved.

 

[matthewwhite]

no spark from the coil.
yeah 12v on positive when ignition is on.
no kill switch
believe the motor to be 1987

 

[matthewwhite]

I'm thinking it could be the sensor inside the distributor?

 

[Scott Danforth]

If you have points, service them. If you have a TBIV, follow the trouble shooting guide in the Mercruiser sticky at the top of the forum

 

[Scott06]

no spark from the coil.
yeah 12v on positive when ignition is on.
no kill switch
believe the motor to be 1987

Do you know if you have points or thunderbolt ignition?

 

[matthewwhite]

its thunderbolt ignition

 

[Scott06]

Heres a troubleshooting guide for TB ignition. Hopefully its just the sensor inside dist https://forums.iboats.com/threads/how-mercruiser-thunderbolt-ignition-systems-work.676476/