Starts but quickly dies, any low tech tips for diagnosis?

[Bextreme04]

Are you useing a mechanical pump?

Yes. I just got the regulator installed last night and was finally able to tune the idle mix in properly. It starts and idles MUCH better now. I still have a problem wit hit trying to stall out about 3-5 seconds after start though. I'm guessing I also need to do some choke adjustment. It will now stumble and almost die, but then recover and go to the high idle like it is supposed to. Previously it would just completely die and then require flooring the pedal and cranking until it starts.

I might just leave it like it is, since I just bought a donor 1997 suburban K2500 and I'm going to swap the L29 and 4L80E into my 1980 K25.

 

[MisterB]

Adjust the choke further to the notches on the left so the choke opens more quickly. Also, make sure when it's below freezing, pump the gas twice and then start it without touching the gas. If it's winter and above freezing, try just one pump and then start it without touching the gas.

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[75gmck25]

If the truck starts and then dies 2-3 seconds later, and its a Quadrajet, it could be the choke pull-off. The main choke spring sets the choke plate full closed on a start-up, but then the vacuum pull-off quickly pulls the choke open a little as soon as you have normal vacuum. If the pull-off is bad or not connected you have to wait for the main choke mechanism to warm up and pull it open, which means it runs too rich (getting no air in) and may stall.

Bruce

 

[80BrownK10]

If the truck starts and then dies 2-3 seconds later, and its a Quadrajet, it could be the choke pull-off. The main choke spring sets the choke plate full closed on a start-up, but then the vacuum pull-off quickly pulls the choke open a little as soon as you have normal vacuum. If the pull-off is bad or not connected you have to wait for the main choke mechanism to warm up and pull it open, which means it runs too rich (getting no air in) and may stall.

Bruce

Mine will do just that. Will crank back and run fine after that. Usually only does this when it's cold out, say 50f or below