Just bought 86 high Sierra

[steam84]

I'm new to the forum, found alot of good information.  I just got an 86 GMC high Sierra, body is a little rough but it has 36 thousand miles and interior is mint.  The Truck sat for 2-3 years, they said it needed a new fuel pump, slapped one in but ripped out all the smog.  Fired the truck up idled perfect needs a carb rebuild but motor sounds great.  A week later i go to start it up again runs perfect but like clock work it just shuts off.  Any suggestion would be appreciated.   I'm going to post some pics soon

[VileZambonie]

More details on your set up

[beastie_3]

can you elaborate some more? Does it all of a sudden shut off or does it sputter? What does your ignition equipment look like? Need replacing? Definitely rebuild the carb.

[1980c10]

Do you have spark?

[steam84]

yea i have spark i just did cap and plugs,  i can rev the motor no problem but like clock work it dies,  no sputtering,  it dies wether im on the gas or not.  A buddy thinks it might be suckings air through a fuel line i have one bad tank,  he thinks it might be the valve the switches the tanks

[Lt.Del]

when it dies, if you look in the carb and activate the accelerator, does gas spurt out into the carb bores?

It dies either because it starves for gas, or, spark stops from what it sounds.  If gas stops and it dies, and you see no gas in carb when activating accelerator, you may have a stuck needle/valve which the float in the carb controls, allowing more or less gas in.   

[beastie_3]

If it doesent sputter before it dies, I dont think its a fuel problem. If it shuts off instantly, similar to when you turn the key off, I would think its electrical.