No Spark - 4.3 Liter Mercruisers

[bobeast]

So the reason for no spark was your voltage drop was below 11 volts, enough to crank the engine but not enough for the ecm to fire the plugs.

I may be having the same issue with one of my 5.7 MPI's. I'm wondering if a bad starter could cause this. The engine seems to crank at a decent speed, but my spark appears weak. Voltage at coil drops to about 10v during crank. All connections are clean and the battery has been recently replaced.

 

[scoflaw]

It certainly could be the starter but I would start with replacing the attached 90 amp fuse first and clean that connection.

 

[bobeast]

It certainly could be the starter but I would start with replacing the attached 90 amp fuse first and clean that connection.

Thanks, Are you referring to the breaker mounted to the slave solenoid assembly? I recently swapped the entire slave solenoid (including that breaker) between my engines, and the problem persists. I do have a shunt on my battery for a NMEA battery monitor. I'll try removing that next I guess.

 

[scoflaw]

Talking about the one mounted directly to the starter. White cube. This directly feeds the 50 amp breaker on top and the alternator.

 

[bobeast]

Talking about the one mounted directly to the starter. White cube. This directly feeds the 50 amp breaker on top and the alternator.

Gotcha.Thanks! I'll try swapping that out.