Technical Starting issue

Not sure if I post tech questions here but going to ask. I have an in-line 6 Chevy 250 motor and a one barrel carb. I have it fire up but as soon as I let go of the key it turns off. I’ve checked to make sure I was getting 12v after the key is let go and I am. Just seeing if anyone could help thanks.


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Check the ballast resistor.

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do you have 12v at coil and dist.?

 

I have a 12V HEI dist. I just found out if I hold the pedal down it will run for a little while.


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With out me holding the key.


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Yes I verified with a multimeter.


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Distributor clamped tight...slipped time? Vacuum leak? Got fuel?

 

Was this a running motor?

 

Got fuel timing still good. Now I no longer have to hold the key I have to keep pushing the pedal or it will die.


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Starting to sound like a lack of fuel delivery somewhere, tank, pump, filter, plugged up carb p***ages...?

 

I’m going from a van to the pump to the carb. I’ve removed the line to the carb and turned the ignition and fuel was coming out.


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sounds more like a big vacuum leak.

 

Can


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How does it run when you hold the key in the " on" position?( you can hold it in "start" for 4 or 5 seconds after it does indeed start)??....als sometimes if you " let go" of the key after the engine starts the springload of the " return from start" feature of some ignition switches will cause the switch to " rotate past" the run position of the switch thus cutting the electricity to the coil.....

 

It sounds like you have the resistor byp*** wire wired to the HEI and need to wire it to either the wire that lead to the ballast resistor originally or to a hot when ign is on pin on the fuse block.
You still may need to keep the byp*** wire hooked up simply because there are some ignition switches that don't have power to the coil in start position depending on the byp*** wire when cranking.

 

Sound like this.


New build?
New issue?
Running engine?
New engine?
Change any parts and this problem started?

ya got fuel, do you have spark at the plugs? Fat blue or orange spark?


I would be looking at a vacuum leak.
Any vacuum lines ya got remove and plug and see what happens .

report back please .