Alpha one no spark

2003 5.0 with thunderbolt ignition....Ive checked ignition switch and kill circuit. i have 12.3 volts on both sides of coil. checked for spark from coil wire . nothing. can anyone tell me how to check for a faulty coil or pickup sensor

you need to follow the thunderbolt diagnostic chart....been posted on this board many times....try using the search button...

Tests for Thunderbolt Ignition:


Tests for Thunderbolt Ignition:
W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts is present remove the coil wire from the distributor cap and connect it to a spark gap tester to ground.

Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test

#2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition timing module (amplifier) is shot and must be replaced.

thanks jack. test confirmed ignition sensor.... another question for you. what is the ignition amplifier , the ecm ?

Yes so to speak..........it is simply a solid state timing advance module.........based on rpm feedback it increases timing. On models with a knock sensor it interacts with the knock sensor and will decrease timing if detonation (ping) is sensed.
The newest generation of timing modules TBV + has mean best timing and uses some other more complicated algorithm to adjust timing.

Professor Jack:

Seeing I'm about to go back to a Mercruiser set up (after years of inboards) I'm saving most of the info you're writing here.

Jeff