Ignition sparks as soon as starter stops cranking

[tkvoice]

I noticed a weird behavior on my 4.3L TKS V6
The engine never starts if I keep the starter cranking. As soon as I stop cranking it starts.

I installed one of those spark tester lights on my distributor cap and it confirmed what I just explained above.... No light until I stop cranking. As soon as I stop the light bulb starts flashing and engine starts.

My question: Is this normal behavior? Or should it be sparking while starter is cranking?

If it's supposed to spark while cranking what would cause it not to spark?

 

[alldodge]

Not knowing your motor serial number but having TKS carb you most likely have EST ignition

Check to see if you have 12V at the coil when cranking
If not look at the key switch

 

[cyclops222]

Battery voltage WHILE YOU ARE CRANKING ? At least 12. 3 vdc.

 

[nola mike]

Not knowing your motor serial number but having TKS carb you most likely have EST ignition

on a 4.3?

 

[alldodge]

on a 4.3?

Your correct I keep forgetting that, it's TBV
Checking is the same

 

[Grub54891]

As stated, if the battery is compromise, it takes a lot of the power away from the ignition. Had a motorcycle that would not start with the starter, but one kick on the foot starter it would fire right up. A proper battery solved the issue. And yes the ignition switch can cause that also, not making the correct contact in the starter mode. Stick a meter at the coil and read the voltage when cranking, a second person will help on that one.

 

[racerone]

Weak battery or starter drawing too much power.

 

[Scott Danforth]

The engine never starts if I keep the starter cranking. As soon as I stop cranking it starts.

classic symptom of bad key switch. confirm with your test meter that you have power to the purple wire during cranking. if yes, keep looking, if no, buy a new key switch.

 

[cyclops222]

If your motor has a big connector plug and socket above the motor ? Reconnect the socket 3 or 4 times to improve pin and socket resistances. Worked on my TKS 5.0L Same symptoms with the key switch,