Truck cranks and starts and dies immediately

[SoCASquare]

Hey guys…truck recently developed an issue where it will crank, and start and then immediately dies.

I initially thought it was fuel related, so I replaced the electric fuel pump (aftermarket tank in the rear), as well
As the inline fuel filter.

After replacing this, issue still there. I started digging into electrical and have replaced the ignition switch, as well as the ignition module inside the HEI distributor which did not help.

I was able to create a jumper wire direct from battery to distributor and truck will fire and idle as it should. I am kind of lost as to where to go from here. It’s as though it’s losing power to distributor once it fires.

454 with HEI Distributor

 

[legopnuematic]

1973 would have had points, if it has HEI now someone added it, good chance they did not bypass the resistor wire (not exactly the potential issue here, but HEI, unlike points wants a healthy 12v source at all times).

On points vehicles they generally bypass the resistor when cranking to give “12 volts” to the coil. This is the “R” terminal on the starter solenoid.

Get a test light and check power at your coil power feed. If it lights when cranking and is not lit in the run position that is the issue.

With HEI you need to get a good constant 12v source that is powered during crank and in the run position and get rid of the resistor wire and disconnect the wire from the “R” terminal.

You must be registered for see images attach

 

[SoCASquare]

1973 would have had points, if it has HEI now someone added it, good chance they did not bypass the resistor wire (not exactly the potential issue here, but HEI, unlike points wants a healthy 12v source at all times).

On points vehicles they generally bypass the resistor when cranking to give “12 volts” to the coil. This is the “R” terminal on the starter solenoid.

Get a test light and check power at your coil power feed. If it lights when cranking and is not lit in the run position that is the issue.

With HEI you need to get a good constant 12v source that is powered during crank and in the run position and get rid of the resistor wire and disconnect the wire from the “R” terminal.

You must be registered for see images attach

Yes, the HEI was retrofitted…I did the test you described and there is power when cranking but not in run position.

Given that, where would I source the appropriate power from to the HEI? I looked for an “IGN” port on the fuse block, but where it should be, looks to be missing. I’m an idiot when it comes to electrical, so that doesn’t help.

You must be registered for see images attach

 

[SoCASquare]

Update: I think I had the wiring on the starter mixed up. I had the green wire on the same post as the yellow wire (see pic) This all started after I installed a new transmission.

Changed the wiring on the starter and now the truck starts and idles, but won’t turn off unless you pull the wire from the coil/distributor ‍.

You must be registered for see images attach

 

[75gmck25]

The wiring colors at your starter are not original.
- red wires appear correct, but there should be a fusible link in the small red wire (maybe it’s just not in the picture). This is constant power to the fuse block.
- yellow wire should be on the R terminal if you have points, and it’s only for points ignition . I would disconnect and cap the wires at both ends.
- the other terminal should be the S terminal (solenoid/start), which is used to activate the starter. Stock color should be purple (IIRC), and it’s only powered in the ignition start position