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.

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[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.

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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.

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[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 ‍.

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[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

 

[SoCASquare]

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

Given that this is an HEI ignition, should a place the green wire where the yellow wire is, and cap the yellow wire?

The condition currently is that the truck will start and run, but not turn off with the key. I believe it’s because the post where the green wire currently is, has constant 12v to it.

 

[Matt69olds]

Since you have HEI, the BEST way to wire it is to find the original resistance wire and remove it. Then you can install a regular wire in the original spot and eliminate the ignition bypass wiring and extra connections at the fuse box. You need a Series 56 male terminal, a couple bucks from Napa.


Disconnect the battery. Find the original resistance wire. Once you have the wire in hand, pull it out of the original wire loom all the way back to the firewall connector. Remove the bolt from the center of the bulkhead connector and seperate the plug.

Next, notice the orientation of the original terminal. Use a pocket screwdriver to compress the locking tab and push the wire out of the connector. It will probably take some effort to push it out, GM used some pretty gooey stuff to seal the connection.

Crimp a piece of 14 gauge wire onto the new series 56 terminal, reinstall it in the original cavity where the resistance wire was, and reassemble everything. Connect the other end of the new wire to the Batt connector of the HEI. Remove the original wiring from the R terminal at the starter.

This will give you a basic idea of what’s involved.

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