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Mercruiser 5.7 carb version.

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pascalmekkelholt

Member
Goodafternoon,

Our mercruiser 5.7 L V8 wont start, it seems to me it wont get any spark to start. It cranks the engine around but no spark. Whe changed the wires and bougies. And whe changed also the oil pressure sensor, and switch to the fuel pump. But now it wont start. Just cranking the engine but no spark
 
TB ignition troubleshooting guide is in this thread Post #4. If it is a 2001 it is probably the TBV not 4 but troubleshooting is the same

Thunderbolt IV ignition problem

I have a Thunderbolt IV system I’ve been going back and forth with since last season. Have replaced cap and rotor, ICM w/ a used one and the original ignition sensor in the distributor with the updated sealed three wire design as opposed to the two terminals and now have an MSD Blaster 2 coil on...
forums.iboats.com forums.iboats.com

if you need a module can find them used on Ebay normally. The module is the expensive part... if its the sensor in the distributor that is not bad cost wise.

Not sure if it says to in the troubleshooting guide disconnect the shift interrupt switch if it is an alpha drive. if switch goes bad or is triggering it will kill the ignition
 
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