Ignition Will Not Fire Until Key Released

[Bob C]

Engines and all ignition components are like new. Had a hard time starting the port engine until I realized it starts right up after I release the key from cranking mode and the key goes into just the running position on the switch; and the engine starts? Thinking the ignition switch? Starboard engine starts as it should. Appreciate any ideas. 1990 270DA with twin 4.3 carbed Mercs. Thanks, Bob

 

[PlayDate]

Does it behave this way on both engines or just one?

 

[Bob C]

Does it behave this way on both engines or just one?

Just the port.

 

[PlayDate]

My money is on the ignition switch. The easy way to tell is clamp a multimeter on the + of the coil and an engine ground. Watch it as you turn the key. If it goes to zero when you are cranking.....definitely the ignition switch.

 

[Bob C]

My money is on the ignition switch. The easy way to tell is clamp a multimeter on the + of the coil and an engine ground. Watch it as you turn the key. If it goes to zero when you are cranking.....definitely the ignition switch.

Thanks, will try that today.

 

[Bob C]

Thans PlayDate, new switch is on order!

 

[scoflaw]

Should have checked the voltage on the purple wire leaving the switch before ordering the part.

 

[PlayDate]

Should have checked the voltage on the purple wire leaving the switch before ordering the part.

Purple wire goes to the coil. If it doesn't have 12 volts there when cranking....the engine is not going to start.

 

[scoflaw]

Purple wire goes to the coil. If it doesn't have 12 volts there when cranking....the engine is not going to start.

Exactly, that's why a mentioned testing for voltage on that switch terminal while cranking to confirm whether or not it's the switch