Motor won't stay running

Hey guys, my chevy 350 engine won't stay running. When I turn the key, it starts but then when I take my hand off the key it dies. Any ideas? Thank you!

What year, What ignition?


if you have a electronic (mercury Thunderbolt V or IV) then the issue may be the key switch.

The key switch has battery +12v going to it (red), then when you turn the key to the crank position the 12 volts goes to that terminal (yellow with red stripe) and also is shared internal to the switch with the RUN terminal (purple) . When you release the key to the run position the 12 volts should now be on that terminal only and no longer on the crank terminal.

So check to see if this is happening. Best to use a test light!!

If it is happening and 12 volts is on the purple with the key in the run position then the issue is down stream in the wiring harness.

Neutral safety wont allow it to crank at all!!

Dead man switch (lanyard) if so equipped may be an issue but I forget how that is wired in right now so check for that also

If you have point ignition then the issue is the starter solenoid on the starter.